Does the following expression represent an identity?

A student of mine created the expression above and believes that it is an identity. However, I subbed in pi/4 for

*x*on both sides and I got different answers... therefore disproving it as an identity. Can someone please confirm this with me?

I also made an attempt to solve the left-side, but didn't go very far because I didn't see much light at the end of the tunnel towards proving the expression:

Look forward to a response! Any help is appreciated!