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Question
secondary 4 | A Maths
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As for sin (pi/2 - A/2), we need to use quadrants triangle and your addition and double angle formulae.
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Use calculator find angle
2) sin(pi()/2-A/2) = cos(A/2)
Cos(A/2) = [(1+Cos(A))/2]^0.5
From 1), find COS(A)