A 356. Quadrilateral ABCD is inscribed in a circle, and the lengths of its sides are AB = 5, BC = 9, CD = 7, and DA= 3. Let x be the unknown length of diagonal AC. (a) In terms of x, write an expression for cos B. (b)In terms of x, write an expression for cos D. (c) A simple relationship holds between angles B and D. Use it to help you find the unknown length x. (d)Find the length of diagonal BD. B 5 3 D %3D 7