SOLUTION: Use double or half angle formula to determine the value of the trigonometric function sin(19pi/12) Do you know how to solve this?? So confusing!!! Thanks!

Question 808517: Use double or half angle formula to determine the value of the trigonometric function sin(19pi/12)
Do you know how to solve this?? So confusing!!! Thanks!
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
Use double or half angle formula to determine the value of the trigonometric function sin(19pi/12)
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use sin half-angle formula:
..
sin(19pi/12)=sin(38π/12)/2=sin(19π/6)/2=sin(3π+π/6)/2
reference angle for (3π+π/6)=7π/6 in quadrant III where sin<0, cos<0
sin(19π/12)=sin(3π+π/6)/2=sin(7π/6)/2=

..
calculator check:(Use sin key set to radians)
sin(19π/12)≈-0.9659..
Exact answer as calculated=≈-0.9659..
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