The reason behind the statement m∠TRS + m∠TRV = 180° is; Angle Addition Postulate
<h3>How to use angle addition postulate?</h3>Angle addition postulate states that if D is the interior of ∠ABC, therefore, the sum of the smaller angles equals the sum of the larger angle, which from the attached image is;
m∠ABD + m∠DBC = m∠ABC.
From the attached image, we want to prove that x = 30°.
Now, T is the interior of straight angle ∠VRS.
m∠VRS = 180° (straight line angle)
Thus, from angle addition postulate, we can say that;
m∠TRS + m∠TRV = 180°.
Read more about two column proofs at;brainly.com/question/1788884
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