# Trigonometric Substitution

Trigonometry and calculus are two most useful branches of mathematics. The applications of those are seen almost everywhere. Though, differentiation and integration are the concepts of calculus, but these, especially integration, can never be understood clearly without a good command over trigonometry. There are various complex looking integrands that cannot be evaluated using usual formulas. These are integrated using trigonometric substitutions.

Trigonometric substitution is the process of plugging trigonometric functions into other expressions which are needed to be integrated. Trigonometric substitutions actually make the expression easier to integrate.

In order to understand this method more clearly, let us learn trig substitution method in detail.