How do I show this equation is not an identity in paragraph form? sin α=square root 1-cos²α

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Answer 1 · 2018-03-23T23:29:42

Can't really do that, because this is a true statement

Using the identity:
#sin^2alpha+cos^2alpha=1#

Start:

#sinalpha= sqrt(1-cos^2alpha)#

#sinalpha= sqrt((sin^2alpha+cos^2alpha)-cos^2alpha)#

#sinalpha= sqrt(sin^2alphacancel(+cos^2alpha)cancel(-cos^2alpha))#

#sinalpha= sqrt(sin^2alpha)#

#sinalpha= sinalpha#