Trigonometric substitution

In mathematics, trigonometric substitution is the substitution of trigonometric functions for other expressions. One may use the trigonometric identities to simplify certain integrals containing radical expressions:Substitution 1. If the integrand contains a2 − x2, letSubstitution 2. If the integrand contains a2 + x2, letSubstitution 3. If the integrand contains x2 − a2, let In mathematics, trigonometric substitution is the substitution of trigonometric functions for other expressions. One may use the trigonometric identities to simplify certain integrals containing radical expressions: