Qus : 1
2
If → a = 4 ˆ j and → b = 3 ˆ j + 4 ˆ k , then the vector form of the component of → a alond → b is
1
18 10 √ 3 ( 3 ˆ j + 4 ˆ k )
2
18 5 ( 3 ˆ j + 4 ˆ k )
3
18 10 √ 13 ( 3 ˆ j + 4 ˆ k )
4
( 3 ˆ j + 4 ˆ k )
Go to Discussion
Solution
Qus : 2
1
If → a = ˆ i − ˆ k , → b = x ˆ i + ˆ j + ( 1 − x ) ˆ k and → c = y ˆ i + x ˆ j + ( 1 + x − y ) ˆ k , then [ → a → b → c ] depends on
1
Neither x nor y
2
Only x
3
Only y
4
Both x and y
Go to Discussion
Solution
Quick Solution
Given:
→ a = ˆ i − ˆ k , → b = x ˆ i + ˆ j + ( 1 − x ) ˆ k , → c = y ˆ i + x ˆ j + ( 1 + x − y ) ˆ k
Form the matrix:
M = [ 1 x y 0 1 x − 1 1 − x 1 + x − y ]
Find the determinant:
det ( M ) = | 1 x y 0 1 x − 1 1 − x 1 + x − y | = 1
Since the determinant is constant and non-zero, the vectors are linearly independent.
The matrix does not depend on x or y
Qus : 3
3
If → a and → b in space, given by → a = ˆ i − 2 ˆ j √ 5 and → b = 2 ˆ i + ˆ j + 3 ˆ k √ 14 , then the value of ( 2 → a + → b ) . [ ( → a × → b ) × ( → a − 2 → b ) ] is
1
3
2
4
3
5
4
6
Go to Discussion
Solution
Qus : 4
1
If → a , → b are unit vectors such that 2 → a + → b = 3 then which of the following statement is true?
1
→ a is parallel to → b
2
→ a is perpendicular to → b
3
→ a is perpendicular to 2 → a + → b
4
→ b is perpendicular to 2 → a + → b
Go to Discussion
Solution
Quick Solution
Given: → a , → b are unit vectors and
2 → a + → b = 3
Take magnitude on both sides:
| 2 → a + → b | = 3 ⇒ | 2 → a + → b | 2 = 9
Use identity:
| 2 → a + → b | 2 = 4 | → a | 2 + | → b | 2 + 4 ( → a ⋅ → b ) = 4 + 1 + 4 ( → a ⋅ → b ) = 5 + 4 ( → a ⋅ → b )
Set equal to 9:
5 + 4 ( → a ⋅ → b ) = 9 ⇒ → a ⋅ → b = 1 ⇒ cos θ = 1 ⇒ θ = 0 ∘
Qus : 5
1
θ = cos − 1 ( 3 √ 10 ) is the angle between → a = ˆ i − 2 x ˆ j + 2 y ˆ k & → b = x ˆ i + ˆ j + y ˆ k then possible values of (x,y) that lie on the locus
1
(0,1)
2
(1,0)
3
(1,1)
4
(0,0)
Go to Discussion
Solution
Qus : 6
2
If a vector having magnitude of 5 units, makes equal angle with each of the three mutually perpendicular axes,then the sum of the magnitude of the projections on each of the axis is
1
15/3 units
2
5 √ 3 units
3
15 √ 3 2
4
None of these
Go to Discussion
Solution
Vector Projection Problem
Given: A vector of magnitude 5 makes equal angles with x, y, and z axes.
To Find: Sum of magnitudes of projections on each axis.
Let angle with each axis be α . Then, from direction cosine identity:
cos 2 α + cos 2 α + cos 2 α = 1 ⇒ 3 cos 2 α = 1 ⇒ cos α = 1 √ 3
Projection on each axis: 5 ⋅ 1 √ 3
Sum = 3 ⋅ 5 √ 3 = 15 √ 3 = 5 √ 3
✅ Final Answer:
5 √ 3
Qus : 8
2
A force of 78 grams acts at the point (2,3,5). The direction ratios of the line of action being 2,2,1 . The magnitude of its moment about the line joining the origin to the point (12,3,4) is
1
24
2
136
3
36
4
0
Go to Discussion
Solution
Qus : 9
2
The position vectors of the vertices
1
1
2
2
3
3
4
4
Go to Discussion
Solution
Qus : 11
2
Let → a , → b , → c be distinct non-negative numbers. If the vectors a ˆ i + a ˆ j + c ˆ k , ˆ i + ˆ k and c ˆ i + c ˆ j + b ˆ k lie in a plane, then c is
1
The Arithmetic Mean of a and b
2
The Geometric Mean of a and b
3
The Harmonic Mean of a and b
4
Equal to zero
Go to Discussion
Solution → a = a ˆ i + a ˆ j + c ˆ k , → b = ˆ i + ˆ k & → c = c ˆ i + c ˆ j + b ˆ k are coplanar.
⇒ | a a c 1 0 1 c c b | = 0
⇒ − a c − a b + a c + c 2 = 0
⇒ c 2 = a b
Qus : 12
4
The value of m for which volume of the parallelepiped is 4 cubic units whose three edges are represented by a = mi + j + k, b = i – j + k, c = i + 2j –k is
1
0
2
-2
3
-1
4
1
Go to Discussion
Solution
Given: Volume of a parallelepiped formed by vectors → a , → b , → c is 4 cubic units.
Vectors:
→ a = m ˆ i + ˆ j + ˆ k
→ b = ˆ i − ˆ j + ˆ k
→ c = ˆ i + 2 ˆ j − ˆ k
Step 1: Volume = | → a ⋅ ( → b × → c ) |
First compute → b × → c :
→ b × → c = | ˆ i ˆ j ˆ k 1 − 1 1 1 2 − 1 | = ˆ i ( ( − 1 ) ( − 1 ) − ( 1 ) ( 2 ) ) − ˆ j ( ( 1 ) ( − 1 ) − ( 1 ) ( 1 ) ) + ˆ k ( ( 1 ) ( 2 ) − ( − 1 ) ( 1 ) ) = ˆ i ( 1 − 2 ) − ˆ j ( − 1 − 1 ) + ˆ k ( 2 + 1 ) = − ˆ i + 2 ˆ j + 3 ˆ k
Step 2: Compute dot product with → a :
→ a ⋅ ( → b × → c ) = ( m ) ( − 1 ) + ( 1 ) ( 2 ) + ( 1 ) ( 3 ) = − m + 2 + 3 = − m + 5
Step 3: Volume = | − m + 5 | = 4
So, | − m + 5 | = 4 ⇒ − m + 5 = ± 4
Case 1: − m + 5 = 4 ⇒ m = 1
Case 2: − m + 5 = − 4 ⇒ m = 9
✅ Final Answer: m = 1 or 9
Qus : 13
2
The number of distinct real values of λ for which the vectors λ 2 ˆ i + ˆ j + ˆ k , ˆ i + λ 2 ˆ j + j and ˆ i + ˆ j + λ 2 ˆ k are coplanar is
1
1
2
2
3
3
4
6
Go to Discussion
Solution
Given: Vectors:
→ a = λ 2 ˆ i + ˆ j + ˆ k
→ b = ˆ i + λ 2 ˆ j + ˆ k
→ c = ˆ i + ˆ j + λ 2 ˆ k
Condition: Vectors are coplanar ⟹ Scalar triple product = 0
→ a ⋅ ( → b × → c ) = 0
Step 1: Use determinant:
→ a ⋅ ( → b × → c ) = | λ 2 1 1 1 λ 2 1 1 1 λ 2 |
Step 2: Expand the determinant:
= λ 2 ( λ 2 ⋅ λ 2 − 1 ⋅ 1 ) − 1 ( 1 ⋅ λ 2 − 1 ⋅ 1 ) + 1 ( 1 ⋅ 1 − λ 2 ⋅ 1 ) = λ 2 ( λ 4 − 1 ) − ( λ 2 − 1 ) + ( 1 − λ 2 )
Simplify:
= λ 6 − λ 2 − λ 2 + 1 + 1 − λ 2 = λ 6 − 3 λ 2 + 2
Step 3: Set scalar triple product to 0:
λ 6 − 3 λ 2 + 2 = 0
Step 4: Let x = λ 2 , then:
x 3 − 3 x + 2 = 0
Factor:
x 3 − 3 x + 2 = ( x − 1 ) 2 ( x + 2 )
So, λ 2 = 1 (double root), or λ 2 = − 2 (discard as it's not real)
Thus, real values of λ are: λ = ± 1
✅ Final Answer: 2 distinct real values
Qus : 14
3
If the volume of the parallelepiped whose adjacent edges are → a = 2 ˆ i + 3 ˆ j + 4 ˆ k , → b = ˆ i + α ˆ j + 2 ˆ k and → c = ˆ i + 2 ˆ j + α ˆ k is 15, then α is equal to
1
1
2
5/2
3
9/2
4
0
Go to Discussion
Solution
Qus : 15
4
If F|= 40N (Newtons), |D| = 3m, and θ = 60 ∘ , then the work done by F acting
from P to Q is
1
60 √ 3 J
2
120 J
3
60 √ 2 J
4
60 J
Go to Discussion
Solution
Formula for work done:
W = | F | ⋅ | D | ⋅ cos θ
Given:
Step 1: Plug in the values:
W = 40 ⋅ 3 ⋅ cos ( 60 ∘ )
Step 2: Use cos ( 60 ∘ ) = 1 2
W = 40 ⋅ 3 ⋅ 1 2 = 60 J
✅ Final Answer: 60 J
Qus : 16
3
Let → a = 2 ˆ i + 2 ˆ j + ˆ k and → b be another vector such that → a . → b = 14 and → a × → b = 3 ˆ i + ˆ j − 8 ˆ k the vector → b =
1
5 ˆ i + ˆ j + 2 ˆ k
2
5 ˆ i − ˆ j − 2 ˆ k
3
5 ˆ i + ˆ j − 2 ˆ k
4
3 ˆ i + ˆ j + 4 ˆ k
Go to Discussion
Solution
Qus : 17
4
A man starts at the origin O and walks a distance of 3 units in the north-
east direction and then walks a distance of 4 units in the north-west
direction to reach the point P. then → O P is equal to
1
1 √ 2 ( − ˆ i + ˆ j )
2
1 2 ( ˆ i + ˆ j )
3
1 √ 2 ( ˆ i − 7 ˆ j )
4
1 √ 2 ( − ˆ i + 7 ˆ j )
Go to Discussion
Solution
A man starts at the origin O , walks 3 units in the north-east direction, then 4 units in the north-west direction to reach point P .
Find the displacement vector → O P .
? Solution:
North-East (45°):
→ A = 3 ⋅ ( 1 √ 2 , 1 √ 2 ) = ( 3 √ 2 , 3 √ 2 )
North-West (135°):
→ B = 4 ⋅ ( − 1 √ 2 , 1 √ 2 ) = ( − 4 √ 2 , 4 √ 2 )
Total Displacement:
→ O P = → A + → B = ( − 1 √ 2 , 7 √ 2 )
✅ Final Answer:
→ O P = ( − 1 √ 2 , 7 √ 2 )
Qus : 18
1
If → a = λ ˆ i + ˆ j − 2 ˆ k , → b = ˆ i + λ ˆ j − 2 ˆ k and → c = ˆ i + ˆ j + ˆ k and [ → a → b → c ] = 7 , then the values of the λ are
1
2,-6
2
6,-2
3
5,-2
4
-4,2
Go to Discussion
Solution
Qus : 19
1
How much work does it take to slide a crate for a distance of 25m along a loading
dock by pulling on it with a 180 N force where the dock is at an angle of 45°
from the horizontal?
1
3.18198 × 10 3 J
2
3.18198 × 10 2 J
3
3.4341 × 10 3 J
4
3.4341 × 10 4 J
Go to Discussion
Solution
Work Done Problem:
A crate is pulled 25 m along a dock with a force of 180 N at an angle of 45° .
✅ Formula Used:
Work = F ⋅ d ⋅ cos ( θ )
✅ Substituting Values:
W = 180 × 25 × cos ( 45 ∘ ) = 180 × 25 × 0.70710678118 = 3181.98052 J
✅ Final Answer (to 5 decimal places):
3.181 × 10 3 Joules
Qus : 20
3
If ( → a × → b ) × → c = → a × ( → b × → c ) , then
1
→ a and → b are collinear
2
→ a and → b are perpendicular
3
→ a and → c are collinear
4
→ a and → c are perpendicular
Go to Discussion
Solution
Qus : 21
1
The length of the projection of → a = 2 ˆ i + 3 ˆ j + ˆ k on → b = − 2 ˆ i + ˆ j + 2 ˆ k , is equal to:
1
1/3
2
2/3
3
-2/3
4
-1/3
Go to Discussion
Solution
Qus : 22
2
Let → a = 2 ˆ i + ˆ j + 2 ˆ k , → b = ˆ i − ˆ j + 2 ˆ k and → c = ˆ i + ˆ j − 2 ˆ k are are three vectors. Then, a vector in the plane of → a and → c whose projection on → b is of magnitude 1 √ 6 is
1
3 ˆ i − 2 ˆ j
2
3 ˆ i + 2 ˆ j
3
2 ˆ i + 3 ˆ j − ˆ k
4
3 ˆ i + 2 ˆ j + ˆ k
Go to Discussion
Solution
Qus : 23
2
If the position vector of A and B relative to O be ˆ i − 4 ˆ j + 3 ˆ k and − ˆ i + 2 ˆ j − ˆ k respectively, then the median through O of ΔABC is:
1
− 2 ˆ i + 2 ˆ j
2
− ˆ j + ˆ k
3
− ˆ i − ˆ j + ˆ k
4
− ˆ i − ˆ j − ˆ k
Go to Discussion
Solution
Qus : 24
4
The area of the triangle formed by the vertices whose position vectors are 3 ˆ i + ˆ j , 5 ˆ i + 2 ˆ j + ˆ k , ˆ i − 2 ˆ j + 3 ˆ k is
1
√ 21 sq. units
2
√ 23 sq. units
3
√ 33 sq. units
4
√ 29 sq. units
Go to Discussion
Solution
Qus : 25
1
If → a , → b and → c are three vectors such that → a × → b = → c , → a . → c = 2 and → b . → c = 1 . If | → b | = 1 , then the value of | → a | is
1
2
2
1
3
3
4
4
Go to Discussion
Solution
Qus : 26
4
Let → a , → b and → c be unit vectors such that the angle between them is cos − 1 { 1 4 } . If → b = 2 → c + λ → a ,
where λ > 0 and → b = 4 , then λ is equal to
1
1/4
2
1/3
3
4
4
3
Go to Discussion
Solution
Qus : 27
2
If → a and → b are twp vectors such that |→ a |=3, |→ b |=4 and |→ a + → b |=1, then the value of | → a − → b | is
1
2
2
7
3
1
4
6
Go to Discussion
Solution
Qus : 28
4
If → a = ˆ i + ˆ j + ˆ k , → b = 2 ˆ i − ˆ j + 3 ˆ k and → c = ˆ i − 2 ˆ j + ˆ k , then a vector of magnitude √ 22 which is parallel to 2 → a − → b + 3 → c is
1
( ˆ i − 4 ˆ j − 2 ˆ k ) √ 22 21
2
( 3 ˆ i − 3 ˆ j − 2 ˆ k )
3
( ˆ i − 4 ˆ j + 2 ˆ k ) √ 22 21
4
( 3 ˆ i − 3 ˆ j + 2 ˆ k )
Go to Discussion
Solution
Qus : 29
2
If the vectors a ˆ i + ˆ j + ˆ k , ˆ i + b ˆ j + ˆ k , ˆ i + ˆ j + c ˆ k , ( a , b , c ≠ 1 ) are coplanar, then 1 1 − a + 1 1 − b + 1 1 − c =
1
0
2
1
3
2
4
3
Go to Discussion
Solution
Qus : 31
4
Let → a = ˆ i + ˆ j and → b = 2 ˆ i − ˆ k , the point of intersection of the lines → r × → a = → b × → a and → r × → b = → a × → b is
1
− ˆ i + ˆ j + ˆ k
2
3 ˆ i − ˆ j + ˆ k
3
ˆ i − ˆ j − ˆ k
4
3 ˆ i + ˆ j − ˆ k
Go to Discussion
Solution
Qus : 32
1
If → a , → b and → c are vectors such that → a +→ b +→ c = 0 and |→ a | =7, → b =5, |→ c | = 3, then the angle between the vectors → b and → c
1
60o
2
30o
3
45o
4
90o
Go to Discussion
Solution
Qus : 33
5
If
,
and
, (a ≠ b ≠ c ≠ 1) are co-planar, then the value of
is
1
- 1
2
-1/2
3
1/2
4
1
Go to Discussion
Solution
Qus : 34
2
Let a , b and c be three vectors having magnitudes 1, 1 and 2 respectively. If a x (a x c ) - b = 0, then the acute angle between a and c is
1
π/4
2
π/6
3
π/3
4
None of these
Go to Discussion
Solution
Qus : 35
4
Let
,
and
be three vector such that |
| = 2, |
| = 3, |
| =
5 and +
+
= 0. The value of
.
+
.
+
.
is
1
38
2
-38
3
19
4
-19
Go to Discussion
Solution
Qus : 36
2
Constant forces → P = 2 ˆ i − 5 ˆ j + 6 ˆ k and → Q = − ˆ i + 2 ˆ j − ˆ k act on a particle. The work done when the particle is
displaced from A whose position vector is 4 ˆ i − 3 ˆ j − 2 ˆ k , to B whose position vector is 6 ˆ i + ˆ j − 3 k ˆ k , is:
1
10 units
2
-15 units
3
-50 units
4
25 units
Go to Discussion
Solution
Qus : 37
2
If
,
and
are unit vectors, then
does not exceeds
1
4
2
9
3
8
4
6
Go to Discussion
Solution
Qus : 38
3
If
= (i + 2j - 3k) and
=(3i -j + 2k), then the angle between (
+
) and (
-
)
1
π/3
2
π/4
3
π/2
4
2π/3
Go to Discussion
Solution
Qus : 39
2
Let
→ a = 2 ˆ i − 3 ˆ j + 4 ˆ k ,
→ b = ˆ i + 2 ˆ j − ˆ k and
→ c = 3 ˆ i + ˆ j + λ ˆ k be the co-terminal edges
of a parallelopiped whose volume is 5 units. Then the value of λ is
1
3
2
2
3
1
4
4
Go to Discussion
Solution
Qus : 40
4
The vector
lies in the plane of the vector
and
and bisects the angle between
and
. Then which of the following gives possible values of
and
?
1
2
3
4
Go to Discussion
Solution
Qus : 41
3
For the vectors → a = − 4 ˆ i + 2 ˆ j , → b = 2 ˆ i + ˆ j and → c = 2 ˆ i + 3 ˆ j , if → c = m → a + n → b then the value of m + n is
1
1/2
2
3/2
3
5/2
4
7/2
Go to Discussion
Solution
Qus : 42
3
A bird is flying in a straight line with velocity vector 10i+6j+k, measured in km/hr. If the starting point is (1,2,3), how much time does it to take to reach a point in space that is 13m high from the ground?
1
600 sec
2
360 sec
3
36 sec
4
60 sec
Go to Discussion
Solution
Qus : 43
4
Angle between → a and → b is 120 ∘ . If | → b | = 2 | → a | and the vectors , → a + x → b , → a − → b are at right angle, then x =
1
1 3
2
1 5
3
2 3
4
2 5
Go to Discussion
Solution
Qus : 44
3
Let → a and → b be two vectors, which of the following vectors are not perpendicular to each other?
1
( → a × → b ) and → a
2
( → a × → b ) and → a + → b
3
( → a + → b ) and → a − → b
4
( → a − → b ) and → a × → b
Go to Discussion
Solution
Qus : 45
1
If → e 1 = ( 1 , 1 , 1 ) and → e 2 = ( 1 , 1 , − 1 ) and → a and → b and two vectors such that → e 2 = → a + 2 → b , then angle between → a and → b
1
cos − 1 ( − 7 11 )
2
cos − 1 ( 7 11 )
3
cos − 1 ( 7 9 )
4
cos − 1 ( 6 √ 2 11 )
Go to Discussion
Solution
Qus : 46
1
If → A = 4 ˆ i + 3 ˆ j + ˆ k and → B = 2 ˆ i − ˆ j + 2 ˆ k , then the unit vector ˆ N perpendicular to the vectors → A and → B ,such that → A , → B , and ˆ N form a right handed system, is:
1
1 √ 185 ( 7 ˆ i − 6 ˆ j − 10 ˆ k )
2
1 7 ( 6 ˆ i + 2 ˆ j + 3 ˆ k )
3
1 √ 21 ( 2 ˆ i + 4 ˆ j − ˆ k )
4
1 √ 21 ( − 2 ˆ i − 4 ˆ j + ˆ k )
Go to Discussion
Solution
Qus : 47
1
The sum of two vectors → a and → b is a vector → c such that | → a | = | → b | = | → c | = 2 . Then, the magnitude of → a − → b is equal to:
1
2 √ 3
2
2
3
√ 3
4
0
Go to Discussion
Solution
Qus : 48
1
If → a = ˆ i − ˆ k , → b = x ˆ i + ˆ j + ( 1 − x ) ˆ k and → c = y ˆ i + x ˆ j + ( 1 + x − y ) ˆ k , then [ → a , → b , → c ] depends on
1
Neither x nor y
2
Only x
3
Only y
4
Both x and y
Go to Discussion
Solution
Qus : 49
1
Let → a = ˆ i + ˆ j + ˆ k , → b = ˆ i − ˆ j + ˆ k and → c = ˆ i − ˆ j − ˆ k be three vectors. A vector → v in the plane of → a and → b whose projection on → c | → c | is 1 √ 3 , is
1
3 ˆ i − ˆ j + 3 ˆ k
2
ˆ i − 3 ˆ j + 3 ˆ k
3
5 ˆ i − 2 ˆ j + 5 ˆ k
4
2 ˆ i − ˆ j + 3 ˆ k
Go to Discussion
Solution
Qus : 50
1
If → a , → b and → c are the position vectors of the vertices A, B, C of a triangle ABC, then the area of
the triangle ABC is
1
1 2 | → a × → b + → b × → c + → c × → a |
2
| → a × → b |
3
1 2 | → a × → b − → b × → c − → c × → a |
4
→ a × ( → b × → c )
Go to Discussion
Solution
Qus : 51
1
If a vector → a makes an equal angle with the coordinate axes and has magnitude 3, then the angle between → a and each of the three coordinate axes is
1
c o s − 1 ( 1 √ 3 )
2
s i n − 1 ( 1 √ 3 )
3
π 6
4
π 3
Go to Discussion
Solution
Qus : 52
1
A cube is made up of 125 one cm. square cubes placed on a table. How many squares are visible only on three sides?
1
4
2
8
3
12
4
16
Go to Discussion
Solution
Qus : 53
1
If → A C = 2 ˆ i + ˆ j + ˆ k and → B D = − ˆ i + 3 ˆ j + 2 ˆ k then the area of the quadrilateral ABCD is
1
5 2 √ 3
2
5 √ 3
3
15 2 √ 3
4
10 √ 3
Go to Discussion
Solution
Qus : 55
3
Two forces F
1 and F
2 are used to pull a car, which met an accident. The angle between the two forces is θ . Find the values of θ for which the resultant force
is equal to
1
θ = 0
2
θ = 45
3
θ = 90
4
θ = 135
Go to Discussion
Solution
Qus : 56
1
If
are four vectors such that
is collinear with
and
is collinear with
then
=
1
0
2
collinear with
3
collinear with
4
collinear with
Go to Discussion
Solution
Qus : 57
3
Forces of magnitude 5, 3, 1 units act in the directions
6i + 2j + 3k, 3i - 2j + 6k, 2i - 3j - 6k respectively on a particle which is displaced from the
point (2, −1, −3) to (5, −1, 1). The total work done by the force is
1
21 units
2
5 units
3
33 units
4
105 units
Go to Discussion
Solution
Qus : 58
1
The position vectors of points A and B are
and
.
Then the position vector of point p dividing AB in
the ratio m : n is
1
2
3
4
None of these
Go to Discussion
Solution
Qus : 59
1
If a, b, c are three non-zero vectors with no two of
which are collinear, a + 2b is collinear with c and b + 3c is collinear with a , then | a + 2b + 6c | will
be equal to
1
0
2
9
3
1
4
None of these
Go to Discussion
Solution
Qus : 60
2
Vertices of the vectors i - 2j + 2k , 2i + j - k and 3i - j + 2k form a triangle. This triangle is
1
Equilateral triangle
2
Right angle triangle
3
Two sides are equal in length
4
None of the above
Go to Discussion
Solution
Qus : 61
3
If the volume of a parallelepiped whose adjacent edges are
a = 2i + 3j + 4k,
b = i + αj + 2k
c = i + 2k + α k
is 15, then α =
1
1
2
5/2
3
9/2
4
0
Go to Discussion
Solution
Qus : 62
3
If → a and → b are vectors in space, given by → a = ˆ i − 2 ˆ j √ 5 and → b = 2 ˆ i + ˆ j + 3 ˆ k √ 14 , then the value of(2\vec{a} + \vec{b}).[(\vec{a} × \vec{b}) × (\vec{a} – 2\vec{b})] is
1
3
2
4
3
5
4
6
Go to Discussion
Solution
Qus : 63
2
Let \vec{A} = 2\hat{i} + \hat{j} – 2\hat{k} and \vec{B} = \hat{i} + \hat{j} , If \vec{C} is a vector such that |\vec{C} – \vec{A}| = 3 and the angle between A × B and C is {30^{\circ}} , then |(\vec{A} × \vec{B}) × \vec{C}| = 3 then the value of \vec{A}.\vec{C} is equal to
1
25/8
2
2
3
5
4
1/8
Go to Discussion
Solution
Qus : 64
4
If \vec{a} and \vec{b} are vectors such that |\vec{a}|=13 , |\vec{b}|=5 and \vec{a} . \vec{b} =60 then the value of |\vec{a} \times \vec{b}| is
1
625
2
225
3
45
4
25
Go to Discussion
Solution
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