Question

If $co{s}^6\alpha +si{n}^6\alpha +Ksi{n}^{2}2\alpha =1$, then K=

• A. $\frac{4}{3}$
• B. $\frac{3}{4}$
• C. $\frac{1}{2}$
• D. 2

Answer 1

The correct option is B

$\frac{3}{4}$

Since $co{s}^6\alpha +si{n}^6\alpha +Ksi{n}^{2}2\alpha =1$ using formula $a^3+b^3=(a+b{)}^3-3ab(a+b)$ and on solving, we get the required result i.e., $K=\frac{3}{4}$