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LESSON
5:SOLVING TRIGONOMETRIC IDENTITIES
Definition: An Identity is a mathematical statement that is true for all variables in the given
domain.
Example 1: x2
+ x = x(x + 1)
This
statement is an identity as it is true for all x in the real number system
Proof: We prove this by showing that the Left side of
the equation equals the Right side.
L.S. = x2 + x R.S.
= x(x + 1)
= x2 + x
Therefore L.S. = R.S. and the identity is proven.
Basic Trigonometric Identities :
1.
Quotient Identity:
2. Pythagorean Identities:
Example 2:
Proof:
Example 3:
Proof:
Example 4:
Proof:
