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Question : 24 of 160
Marks:
+1,
-0
Solution:
We have,
‌4‌cos‌‌cos‌sin‌5θ‌=2(cos‌5‌θ+cos‌2‌θ)sin‌5θ‌‌‌(∵2‌cos‌A‌cos‌B=cos(A+B)+cos(A−B))‌=2sin‌5θ‌cos‌5‌θ+2sin‌5θ‌cos‌2‌θ‌=sin‌10θ+sin‌7θ+sin‌3θ‌(∵2sin‌A‌cos‌B=sin‌(A+B)+sin‌(A−B))
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