How do you integrate $int dx/sqrt(81-9x^2)$ using trig substitutions?

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Answer 1 · 2016-11-03T19:01:33

$1/3 *arcsin (x/3) +C$

Let x= 3sin u, so that dx= 3 cos u du

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How do you integrate int dx/sqrt(81-9x^2)int dx/sqrt(81-9x^2) using trig substitutions?