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Thursday, April 11, 2013

Proving Trigonometric Identities, 4

Category: Trigonometry

"Published in Newark, California, USA"

If A + B + C = 180°, prove that



Solution:

Consider the given equation above



In proving of trigonometric identities, we have to choose first the more complicated part and then simplify until it match with the other side of the equation. In this case, we have to choose the right side of the equation as follows





Use the Sum and Product Formula, we have













but









Therefore, the above equation becomes






















Therefore, the identity is correct for