Question

prove that, sin (45+theta) sin(45°-theta)=1/2cos2theta
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Answer 1

Answer:

use compound angle identity

sin75.sin15=sin(45+30).sin(45-30)= 1/2 .cos2.30

= 1/2 .cos 60 use special angle value for cos60

= 1/2 x 1/2 = 1/4