How to solve this identity? Thank you!

You need to prove that cotxcoty=sin(yx)sinxsiny

Thank you very much!

1 Answer
Dec 8, 2017

see explanation

Explanation:

using the trigonometric identities

xsin(yx)=sinycosxcosysinx

xcotx=cosxsinx

consider the left side

cotxcoty

=cosxsinxcosysiny

=cosxsinysinxcosysinxsiny

=sin(yx)sinxsiny

= right side verified