Drawing a right triangle to simply the given expressions

[Johnyi]

Homework Statement

Cos(Tan^-1(x))

Homework Equations

The Attempt at a Solution

Dont know how drawing a right triangle would do anything, don't know what to plug in.

 

[Dick]

Homework Statement

Cos(Tan^-1(x))

Homework Equations

The Attempt at a Solution

Dont know how drawing a right triangle would do anything, don't know what to plug in.

Draw a triangle with an angle whose tangent is x. Any one. For example, opposite side equals x and adjacent side equals 1. Then find the hypotenuse using the pythagorean theorem.

 

[Johnyi]

Have another question for a whole new problem...did not want to start a new thread because i felt some people would think i would be spamming.
1. Homework Statement
Sin(sec^-1(sqrt(x^2+16)/4))

2. Homework Equations
3. The Attempt at a Solution
I did the math and ended up getting x^2-1 as the opposite, but the answers on the back of the book say other wise.

 

[Johnyi]

Bump!

 

[HallsofIvy]

This was answered in the "Precalculus homework" section.