Explanation:
Since we have given that
1. Ray ST is perpendicular to Ray SR. - f) Given
2 ∠RST is a right angle - c) Definition of perpendicular lines
3. m∠RST = 90° - e) Definition of right angle
4. m∠1 + m∠2 = m∠RST -d) Angle addition theorem
5. m∠1 + m∠2 = 90° - a) Substitution
6. m∠1 = 90° - m∠2 - b) Subtraction property of equality