Question

Help Please!
If tan θ = 20/21, what is cos θ?

Answer 1

We can use SOH CAH TOA.

We know that the legs, being Opposite and Adjacent, are 20 and 21. Using Pythagorean Theorem, we see the Hypotenuse is 29.

Then, using Adjacent over Hypotenuse, we know cos θ = 21/29.