Given: mZWOz = 90° Prove: mZWOX = 90° Complete the proof: Suppose mZWOX = 90°. By the LWOX is supplementary to ZWOZ, therefore mZWOX mZwOz = 180°. By the assumption and the substitution property of equality, 90° mZWOZ = 180°. Using the subtraction property of equality, the measure of angle WOZ = 90°, which contradicts the given. Therefore, the assumption is not true, and mZWOX = 90°. Given: mZWOz = 90° Prove: mZWOX = 90° Complete the proof: Suppose mZWOX = 90°. By the LWOX is supplementary to ZWOZ, therefore mZWOX mZwOz = 180°. By the assumption and the substitution property of equality, 90° mZWOZ = 180°. Using the subtraction property of equality, the measure of angle WOZ = 90°, which contradicts the given. Therefore, the assumption is not true, and mZWOX = 90°.