Hello, viet!

a) Express in term of : .

We will need the identity: .

Recall that an inverse trig value is anangle.

Let

Since , we have:

. . and Pythagorus gives us:

Hence: .

The problem becomes: .

. . . . . .

b) Find: .

We have: .

Then: .

. . Hence: .

And: .

. . Hence: .

The problem becomes: .

Multiply top and bottom by

I hope I didn't make any stupid blunders . . .