How do you express sin(π12)cos(π8) without products of trigonometric functions?

1 Answer
Dec 21, 2016

(12)[sin(π24)+(12)sin(5π24)]

Explanation:

P=sin(π12).cos(π8)
Use trig identity:
sina.cosb=(12)[sin(ab)+(12)(sin(a+b)]
We have:
sin(ab)=sin((π8)(π12))=sin(π24)
sin(a+b)=sin((π8)+(π12))=sin(5π24)
There for, P can be expressed as:
P=(12)[sin(π24)+(12)sin(5π24)]