How do you prove that sinytany=cosy is not an identity by showing a counterexample?
1 Answer
Jan 29, 2017
It is not an identity. See explanation.
Explanation:
We have
sinytany=cosy
This can be written as
siny*siny/cosy=cosy" " (tany=siny/cosy )
Solving this we get
sin^2y=cos^2y
This will be true only when
For example,
As a counterexample, we can say
but
Hope that helps!