Complete the coordinate proof of the theorem. Given: ABCD is a square. Prove: The diagonals of ABCD are perpendicular. Square in quadrant 1 of the coordinate plane with vertices at A begin ordered pair 0 comma 0 end ordered pair, B, C and D begin ordered pair 0 comma a end ordered pair. Enter your answers in the boxes. The coordinates of square ABCD are A(0, 0), B(, 0), C(, a), and D(0, a). The slope of AC⎯⎯⎯⎯⎯ , when simplified, is equal to . The slope of BD⎯⎯⎯⎯⎯, when simplified, is equal to −1 . The product of the slopes is equal to . Therefore, the diagonals of ABCD are perpendicular.