Simplifying an Expression Involving Inverse Trigonometric Functions

Carl363

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Jan 9, 2017
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Hey guys, first post here!
My precalculus book does not explain how to do this very well and any guidance would be much appreciated!

The problem is, cos(sin-1x-tan-1y)

The -1s are exponents.
Thanks for the help,
Carl
 
Hey guys, first post here!
My precalculus book does not explain how to do this very well and any guidance would be much appreciated!

The problem is, cos(sin-1x-tan-1y)

The -1s are exponents.
Thanks for the help,
Carl
Standard is to write "exponents" as "^(-1)". Although, strictly speaking, the "-1" here is not an "exponent"- sin^(-1)(x) is the inverse function, the funct, v, such that f(sin^(-)(x))= sin^(-1)(f(x))= x, not 1/sin(x).

This problem would be easy if it were just "cos(sin^(-1)(x))" because, for any u, cos(u)= sqrt(1- sin^2(u)) so that cos(sin^(-1)(x))= sqrt(1- (sin(sin^(-1)(x))^2)= sqrt(1- x^2) because, of course, sin(sin^(-1)(x))= x.

So, do you know any ways to simplify cos(a- b) into functions of a and b separately?
 
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