Question
If A, B, C are the angles of a triangle, then
sin(B+C2)= ___.
Answer: Option B
:
B
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:
B
A+B+C=180∘
(sum of angles of a triangle)
⟹B+C=180∘−A
∴B+C2=180∘−A2
B+C2=90∘−A2
Taking sine on both sides we get,
sin(B+C2)=sin(90∘−A2)
∴sin(B+C2)=cosA2
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