Given that sin theta = 21/29, what is the value of cos theta, for 0 < theta < 90?

Answer: The cos (theta) would be 20/29.

First, we need to find the measure of the missing side in this right triangle. Let's use the Pythagorean Theorem.

A^2 + 21^2 = 29^2

Solving this gives an adjacent side value of 20.

Now, we can write the cosine ration of adjacent over hypotenuse.

Cos (theta) = 20/29