1. We are told TR is congruent to TN and that TO is congruent to TS. 2. We are told that TS is perpendicular to PR and that TO is perpendicular to NP. 3. Thus, right angles are formed in both cases. Since all right angles measure 90 degrees, angle NOT is congruent to angle TSR. 4. The triangles are congruent by SAS. 5. By the definition of congruent triangles, the corresponding angles, angle R and angle N, are also congruent.