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if cos(angle)=-sin (angle) then what is sin^2(angle) ? 

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ssdixon | Student, Undergraduate | (Level 1) Salutatorian

Posted May 6, 2012 at 5:14 AM via web

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if cos(angle)=-sin (angle) then what is sin^2(angle) ? 

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beckden | High School Teacher | (Level 1) Educator

Posted May 6, 2012 at 6:07 AM (Answer #1)

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`cos(angle) = -sin(angle)` when `angle = (3pi)/4` and `(7pi)/4`

`sin(angle) = +-1/2`

so `sin^2(angle) = 1/4`

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ayush01 | Student, Grade 10 | (Level 1) Honors

Posted August 9, 2012 at 9:39 AM (Answer #2)

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let angle be A

now cosA=-sin A

squaring both sides,

cos^2A=sin^2A

or, 1-sin^2A=sin^2A

or, 1=2sin^2A

or 1/2=sin^2A

Therefore, in the given condition, sin ^2 (angle) =1/2

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