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This document contains a step-by-step proof of a trigonometric identity. [1] It begins by working with the right side of the identity, obtaining a common denominator and simplifying the numerator using a Pythagorean identity. [2] It then works through the same steps for the left side of the identity. [3] After bringing the terms from both sides together, it simplifies and verifies the original identity, concluding with "Q.E.D." to indicate the proof is complete.