SOLUTION: could you please help me find sin(2x) and cos(2x) sinx= 3/&#8730;10 and pi/2 < x < pi the answers that I was getting were very wrong

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Question 1094866: could you please help me find sin(2x) and cos(2x)
sinx= 3/√10 and pi/2 < x < pi
the answers that I was getting were very wrong

Found 2 solutions by Alan3354, rothauserc:
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
What answers did you get, and how did you get them?
================
How do you know they're "very wrong" and not just wrong?

Answer by rothauserc(4718)   (Show Source): You can put this solution on YOUR website!
the inverse sin of 3/square root(10) = 71.5651
:
x = 180 - 71.5651 = 108.4349
:
sin(2x) = sin(2 * 108.4349) = -0.6
:
cos(2x) = cos(2 * 108.4349) = -0.8
:

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