The identity is verified. $(1+sin~y)[1+sin(-y)]=cos^2y$
Work Step by Step
$sin^2y+cos^2y=1$ $cos^2y=1-sin^2y$ $(1+sin~y)[1+sin(-y)]=(1+sin~y)(1-sin~y)=1^2-sin^2y=cos^2y$
You can help us out by revising, improving and updating this answer.Update this answer
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.