
<em><u>Solution:</u></em>
<em><u>Given trignometric expression is:</u></em>

We have to evaluate the above expression
<em><u>Let us use the trignometric identities</u></em>

<em><u>Also, use another trignometric identitiy</u></em>

Therefore, upon rearranging we get,

<em><u>Apply these two identities in given expression</u></em>

Thus value of given expression is -1