Well, with a little bit of work with the Pythagorean Theorem, which in a right triangle, which this is, where the sum of the squares of the lengths of the legs is equal to the square of the length of the hypotenuse, and the equation is a^2 + b^2 = c^2, but you know what A and C is, therefore, you would have to find B. Therefore, you will need to find B, and the Hypotenuse, and the hypotenuse is always the opposite of the right angle, and is always the longest side of the triangle, which is C, therefore, the hypotenuse is 41. You need to find B, like I stated before. B is a leg, therefore you will do 1600 + ____ = 1681 (I found 1600 by squaring 40, which is A, and I found 1681 by squaring 41, which is C.) Therefore, what gives you 81? 9! Your answer is 9!
