Question 505227: Decide whether the equation is a trigonometric identiye explain your reasoning.
cos^2x(1+tan^2x)=1
secxtanx(1-sin^2x)=sinx
cos^2(2x)-sin^2=0
Answer by lwsshak3(11628)   (Show Source):
You can put this solution on YOUR website! Decide whether the equation is a trigonometric identity explain your reasoning.
cos^2x(1+tan^2x)=1
secxtanx(1-sin^2x)=sinx
cos^2(2x)-sin^2=0
**
cos^2x(1+tan^2x)=1
cos^2x+sin^2x/cos^2x=1
cos^2x+sin^2x=1
left side = right side, therefore, equation is an identity
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secxtanx(1-sin^2x)=sinx
(1/cosx*sinx/cosx)(1-1+cos^2x
(sinx/cos^2x)(cos^2x)=sinx
left side = right side, therefore, equation is an identity
..
cos^2(2x)-sin^2=0
cos^2x-sin^2x-sin^2x
cos^2x-2sin^2x
cos^2x-2+2cos^2x
3cos^2x-2≠0
left side ≠ right side, therefore, equation is not an identity
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