SOLUTION: Find exact value of cos 3pi/4 sin 7pi/12

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Question 564116: Find exact value of
cos 3pi/4
sin 7pi/12
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Find exact value of
cos 3pi/4=-√2/2 (in quadrant II where cos<0)
..
sin 7pi/12=sin(3π/12+4π/12)=sin(π/4+π/3)
use addition formula for sin
sin(π/4+π/3)=sin(π/4)cos(π/3)+cos(π/4)sin(π/3)
=√2/2*1/2+√2/2*√3/2=√2/4+√6/4
sin 7pi/12=(√2+√6)/4