Chapter 3 - Section 3.3 - Isosceles Triangles - Exercises - Page 153: 35

1. We are told RU is congruent to VU, so angle V is congruent to angle R. 2. We are also told that angle 1 and angle three are congruent. 3. Thus, by the angle-side-angle congruency postulate, RUS and VUT are congruent. 4. This means TU equals SU. 5. Since these two sides are equal STU is isosceles.