 In this video, we present the solution to question number one for practice exam number two for math 1060, in which case we're asked to compute the exact value of arc tangent of one without using a calculator. Well, whenever you see an inverse trigonometric function, you should think of it as this is the angle we're trying to find. We're trying to find an angle. Looking at the answers here, all these angles are in radiance, so we need to find the answer in radiance here. So moving the inverse function to the other side of the equation, what we're trying to solve is the equation one equals tangent of theta. So we're trying to figure out when is tangent equal to one? Well, since tangent, of course, is just sine over cosine, we see right here, we're really trying to figure out when is sine equal to cosine. And so with the standard domain, cosine and sine are equal to each other in the first quadrant at a 45 degree angle or pi force. And so we see that arc tangent of one is equal to pi over four. That's when tangent is equal to one.