Convert the inverse cos and sin functions into inverse tan functions
tan⁻¹ + tan⁻¹
[∴This can be found taking a right triangle and labeling the sides, and then using Pythagorean Theorem, we can find the missing side and take the ratio of tan]
<u>Identity</u>
tan⁻¹ x + tan⁻¹ y = tan⁻¹
Using this identity, we can simplify our earlier equation!