SOLUTION: Use the sum or different to find he exact value of each trigonometric function a) tan(π)/(12) b) cos 150 c) cos(7π)/(12)

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Question 507475: Use the sum or different to find he exact value of each trigonometric function
a) tan(π)/(12)
b) cos 150
c) cos(7π)/(12)
Answer by lwsshak3(11628) About Me  (Show Source):
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Use the sum or different to find he exact value of each trigonometric function
a) tan(π)/(12)
b) cos 150
c) cos(7π)/(12)
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a) tan(π/12)=tan(4π/12-3π/12)=tan(π/3-π/4)
use identity: tan(s-t)=(tan s-tan t)/(1+tan s tan t)
..
b)cos(150)=cos(90+60)
use identity: cos(s+t)=cos s cos t-sin s sin t
..
c) cos(7π/12)=cos(4π/12+3π/12)=cos(π/3+π/4)
use identity: cos(s+t)=cos s cos t-sin s sin t
..
Student to finish problem. Check answers with calculators (be sure you are on the correct degree or radian mode)