SOLUTION: If cosx=-3/5, and x is in between 180 and 360 degrees, find the value of sinx

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Question 1099379: If cosx=-3/5, and x is in between 180 and 360 degrees, find the value of sinx
Found 2 solutions by Boreal, ikleyn:
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
cos x is negative in the third quadrant, not the fourth, and sin x is negative in the third quadrant.
cos^2x + sin ^2 x=1
Therefore, sin ^2 x=1=9/25=16/25
sin x=-4/5

Answer by ikleyn(52833) About Me  (Show Source):
You can put this solution on YOUR website!
.
. . . then the angle x terminates in QIII, where sine is negative function, and 

sin(x) = -sqrt%281-cos%5E2%28x%29%29 = -sqrt%281-%28-3%2F5%29%5E2%29 = -sqrt%281-9%2F25%29 = -sqrt%28%2825-9%29%2F25%29 -= -sqrt%2816%2F25%29 = -4%2F5.