Match each number with its correct letter according to the picture1. Ray ST is perpendicular to Ray SR. a) Substitution 2. ∠RST is a right angle. b) Subtraction property of equality 3. m∠RST = 90° c) Definition of perpendicular lines 4. m∠1 + m∠2 = m∠RST d) Angle addition theorem 5. m∠1 + m∠2 = 90° e) Definition of right angle 6. m∠1 = 90° - m∠2 f) Given