Question

Can Any one solve the question please i am tired of solving it can anyone do it for me .
this question is from class 10 trigonometry from sub-multiple angle chapter
please solve it step by step

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Answer 1

Answer:

Formula: $a^2 - b^2 = (a+b)(a-b)$

Applying that to the LHS we get,

$(cos^2 \frac{\theta}{6} + sin^2 \frac{\theta}{6})(cos^2 \frac{\theta}{6} - sin^2 \frac{\theta}{6})$

Since $sin^x + cos ^ x =1$ the LHS becomes simply $(cos^2 \frac{\theta}{6} - sin^2 \frac{\theta}{6})$

Formula: $cos 2x = cos^2x - sin^2 x$

Applying that formula we get LHS = $cos \frac{\theta}{3}$ which = RHS

Hence proved.