find the no.of solutions of $\displaystyle 1+\cos10x\cos6x=2\cos^2 x + \sin^2 x$ where 20○<x<80○ where ○ refers degree
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Originally Posted by grgrsanjay find the no.of solutions of $\displaystyle 1+\cos10x\cos6x=2\cos^2 x + \sin^2 x$ where 20○<x<80○ where ○ refers degree subtract $\displaystyle sin^2x$ from both sides, then use a well-known trig identity to simplify.
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