SOLUTION: Please help me solve this equation: If cos(a)=8/17 and 270° < a < 360°, then sin(a) equals? Thankyou

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Question 797527: Please help me solve this equation: If cos(a)=8/17 and 270° < a < 360°, then sin(a) equals?
Thankyou
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
If cos(a)=8/17 and 270° < a < 360°, then sin(a) equals?
reference angle (a) is in quadrant IV where cos>0 and sin<0
sin(a)=-√(1-cos^2(a))=-√(1-(8/17)^2)=-√(1-(64/289)=-√(225/289)=-15/17