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Question
In ΔABC, `cos (A + C)/2` is equal to ______.
Options
0
1
`cos B/2`
`sin B/2`
MCQ
Fill in the Blanks
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Solution
In ΔABC, `cos (A + C)/2` is equal to `underlinebb(sin B/2)`.
Explanation:
In any triangle A + B + C = 180°.
So, A + C = 180° – B and `(A + C)/2 = 90° - B/2`.
Therefore, `cos ((A + C)/2)`
= `cos (90° - B/2)`
= `sin (B/2)`
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