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Verifying Trigonometric Identities. In verifying identities, we are trying to demonstrate that the left side of the identity is equivalent to the right side of the identity .
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Verifying Trigonometric Identities • In verifying identities, we are trying to demonstrate that the left side of the identity is equivalent to the right side of the identity. • In verifying identities, do not think of the process as solving an equation. For example, don’t add the same expression to both sides. • We do not know that the left side is equal to the right side in an identity. That is what we are trying to prove.
Process to Verify an Identity • Start with one side, usually the more complicated side. • Use identities to simplify and change form. • Use algebraic manipulation: multiply up and down by the same expression, factor expressions, etc. • Try writing all trigonometric expressions in terms of sine and cosine. • Keep working until you get the expression on the other side of the identity.
Example 1: • Verify the identity: • Start with the left side, and try to use valid operations to get the right side.
Example 2: • Verify the identity: • Start with the left side, and try to use valid operations to get the right side.
Example 3: • Verify the identity:
Example 4: • Verify the identity: