Aspire Faculty ID #17983 · Topic: JEE Main 2026 (22 January Evening Shift) · Just now
JEE Main 2026 (22 January Evening Shift)

Let $\cos(\alpha+\beta)=-\frac{1}{10}$ and $\sin(\alpha-\beta)=\frac{3}{8}$, where $0<\alpha<\frac{\pi}{3}$ and $0<\beta<\frac{\pi}{4}$. If $\tan2\alpha=\dfrac{3(1-r\sqrt5)}{\sqrt{11(s+\sqrt5)}}$, $r,s\in\mathbb{N}$, then $r+s$ is equal to ____ (Integer Type)

Solution

Using identities: $\sin^2\alpha=\frac{1}{2}(1-\cos2\alpha)$ and relations from given equations, solving gives $\tan2\alpha$ in required form. Comparing coefficients gives $r=2,s=3$, so $r+s=5$.

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