McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
3. Proving Triangles Congruent-SSS, SAS
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Exercise 5 Page 358

Do the two triangles have a common side? How many pairs of congruent sides do you have?

See solution.

Practice makes perfect
We are asked to write a paragraph proof to prove that triangles QRT and SRT are congruent. Here is what we are given. Given:& QR ≅ SR, ST ≅ QT Two pairs of sides in the triangles are congruent. Let's then mark the congruent sides in the given diagram.

Notice that the side RT is common for both △ QRT and △ SRT. By the Reflexive Property of Congruent Segments we have RT is congruent to itself. Let's write down what we know so far. cc QR ≅ SR & Side QT ≅ ST & Side RT ≅ RT & Side All corresponding sides in the triangles are congruent. By the Side-Side-Side (SSS) Congruence Postulate, we can conclude that triangles QRT and SRT are congruent. △ QRT ≅ △ SRT

Paragraph Proof

Let's now summarize our findings in one paragraph.

Given:& QR ≅ SR, ST ≅ QT Prove:& △ QRT ≅ △ SRT

Proof: The side RT is common for both △ QRT and △ SRT, and by the Reflexive Property of Congruent Segments we have RT ≅ RT. Therefore, the three sides of △ QRT are congruent to the three sides of △ SRT. By the Side-Side-Side (SSS) Congruence Postulate we conclude that △ QRT ≅ △ SRT.