sin²x-1 and cos³y+cos(y)sin²(y) simplified?

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I'm having a bit of trouble on my calculus worksheet, can someone explain to me how to simplify sin²x-1 and cos³y+cos(y)sin²(y)? Thank you!

2007-09-06 16:44:55 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics

sin^2x - 1= (sin(x) + 1)(sin(x)-1)

cos^3 (y) + cos (y) sin ^2(y) =
cos(y) (cos^2(y) + sin^2(y)) =
cos(y)(1) = cosy

2007-09-06 16:55:02 · answer #1 · answered by mohanrao d 7 · 0⤊ 0⤋

Simplify.

sinÂ²x - 1 = -cosÂ²x

cosÂ³y + (cos y)(sinÂ²y) = (cos y)(cosÂ²y + sinÂ²y)
= (cos y)*1 = cos y

2007-09-06 23:55:49 · answer #2 · answered by Northstar 7 · 0⤊ 0⤋

sinÂ²x-1 = - cosÂ²x

cosÂ³y+cos(y)sinÂ²(y) = cosy ( cosÂ²y+sinÂ²y ) = cosy

( because cosÂ²y+sinÂ²y = 1 )

2007-09-06 23:52:49 · answer #3 · answered by Madhukar 7 · 0⤊ 0⤋