# Homework Help: Drawing a right triangle to simply the given expressions

1. Feb 18, 2012

### Johnyi

1. The problem statement, all variables and given/known data

Cos(Tan^-1(x))

2. Relevant equations

3. The attempt at a solution
Dont know how drawing a right triangle would do anything, dont know what to plug in.

2. Feb 18, 2012

### Dick

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.

3. Feb 18, 2012

### 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. The problem statement, all variables and given/known data
Sin(sec^-1(sqrt(x^2+16)/4))

2. Relevant 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.

4. Feb 18, 2012

### Johnyi

Bump!

5. Feb 19, 2012

### HallsofIvy

This was answered in the "Precalculus homework" section.