<p>Hi guys, our teacher gave us this huge worksheet of related rates problems but I'm having trouble answering one of them...Can anyone help? By the way, the answer is posted after the question, but I just need to know HOW to solve it. Thanks in advance!</p>
<p>In triangle ABC, AB = 15 in and AC = 20 in. The angle between AB and BC is increasing at pi/90 radians per second. How fast is the length of the third side changing when the angle between the sides is pi/3 radians.</p>
<p>Find the length of the third side in terms of known values and the angle between the sides. (without looking at the problem too closely, you'd probably want to use law of cosines or something.) Differentiate the length with respect to time. Then you should get something like dL/dt = f(theta)dtheta/dt, where f is some function, so just substitute the values.</p>