This is a classic right triangle trig problem! She is standing 210 from the tower and the angle is 11 degrees. The height of the tower is one leg of the triangle and the distance from her to the tower is the other leg. In order to find out how tall the tower is, you would use the identity that allows for the side opposite the reference angle and the side adjacent to the reference angle. That is tangent. So tan 11 = x/210. Make sure you have your calculator in degree mode for this or your answer will be way wrong! To solve for x, multiply both sides by 210 to get 210 tan 11 = x. Entering that into your calculator just like that gives you an x value of 40.8 yd.