14. Look at the triangle shown on the right. The Pythagorean theorem states that the sum of the squares of the legs of a triangle is equal to the square of the hypotenuse. Margaret uses this theorem to simplify and rewrite the expression (b/r)2 + (a/r)2 using the triangle shown. Which trigonometric identity can she prove with her expression? b A. sin2 0 + cos2 0 = 1 B. 1 + tan2 0 = sec2 0 e C. 1 + cot2 0 = csc2 0 D. csc2 0 + sec2 0 = 1 a