SOLUTION: cos theta=3/5, while 3pi/2 < theta < 2pi what is sin 2theta? I know that the equation is sin2 theta=2sin theta cos theta i just do not know how to solve from there

Algebra ->  Inequalities -> SOLUTION: cos theta=3/5, while 3pi/2 < theta < 2pi what is sin 2theta? I know that the equation is sin2 theta=2sin theta cos theta i just do not know how to solve from there      Log On


   

Question 1029439: cos theta=3/5, while 3pi/2 < theta < 2pi what is sin 2theta? I know that the equation is sin2 theta=2sin theta cos theta i just do not know how to solve from there
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Use
sin%5E2%28theta%29%2Bcos%5E2%28theta%29=1
to solve for sin%28theta%29
sin%5E2%28theta%29%2B%289%2F25%29=1
sin%5E2%28theta%29=16%2F25}
sin%28theta%29=0+%2B-+4%2F5
Since it's in Q4, sin%28theta%29%3C0
sin%28theta%29=-4%2F5
So then,
sin%282%2Atheta%29=2sin%28theta%29cos%28theta%29
sin%282%2Atheta%29=2%28-4%2F5%29%283%2F5%29
sin%282%2Atheta%29=-24%2F25