If
Step 4: Distribute the 2 in the second part of the expression to get
Step 1 :Step 1: Use the trigonometric identity
Step 2 :Step 2: Group the terms to factor by grouping. The expression now becomes
Step 3 :Step 3: Use the Pythagorean trigonometric identity
Step 4 :Step 4: Distribute the 2 in the second part of the expression to get