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ABC is a triangle. sin((B+C)/(2))=...

ABC is a triangle. `sin((B+C)/(2))=`

A

`(A)/(2)`

B

`cos(A)/(2)`

C

`sinA`

D

`cosA`

Text Solution

Verified by Experts

The correct Answer is:
B
Since ABC is a triangle,
`:.angleA+angleB+angleC=180^(@)or,angleB+angleC=180^(@)-angleAor,(angleB+angleC)/(2)=90^(@)-(angleA)/(2)`
`:.sin((B+C)/(2))=sin(90^(@)-(A)/(2))=cos""(A)/(2)`.
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CALCUTTA BOOK HOUSE-TRIGONOMETRIC RATIOS OF COMPLEMENTARY ANGLES -EXERCISE
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