# Techniques of Integration: Trigonometric substitutions The familiar trigonometric identities may be used to eliminate radicals from integrals. Specially when these integrals involve and .

1
For set . In this case we talk about sine-substitution.
2
For set . In this case we talk about tangent-substitution.
3
For set . In this case we talk about secant-substitution.

The expressions and should be seen as a constant plus-minus a square of a function. In this case, x represents a function and a a constant. For example can be seen as one of the two previous expressions. Indeed, if we complete the square we get where . So from the above substitutions, we will set .

The following examples illustrate how to use trigonometric substitutions : [Calculus] [Next Example]
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