SOLUTION: if cos\theta =2x, then what is sin\theta

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Question 1152884: if cos\theta =2x, then what is sin\theta




Found 2 solutions by Alan3354, MathLover1:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
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Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

given:
cos%28theta%29+=2x
find:+sin%28theta%29
since sin%5E2%28theta%29%2Bcos%5E2%28theta%29=1=>sin%5E2%28theta%29=1-cos%5E2%28theta%29
since given cos%28theta%29+=2x=>cos%5E2%28theta%29=4x%5E2
then
sin%5E2%28theta%29=1-4x%5E2
+sin%28theta%29=sqrt%281-4x%5E2%29