Ruby began a plan for this proof. Since 1 3, then m 1 = m 3. She knows that m 1 + m 2 = m QVS and m 3 + m 2 = m TVR by the angle addition postulate. If she can get m QVS and m TVR to both equal the same expression, she can use the transitive property of equality to set them equal to each other. How can Ruby get m QVS and m TVR to both equal the same expression? Rays Q, R, S, and T extend from point V. Angle Q V R is labeled 1, R V S is 2, and S V T is 3. Given: 13 Prove: QVSTVR CLEAR CHECK She can subtract m 1 from both sides of m 1 + m 2 = m QVS, and m 3 from both sides of m 3 + m 2 = m TVR. She can substitute m 3 for m 1 in m 1 + m 2 = m QVS. She can measure QVS and QVR with a protractor to prove they are the same. She can prove that ray VR bisects QVS and ray VS bisects TVR. Then she