Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
3. Proving Triangles Similar
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Exercise 10 Page 455

Compare the ratios of corresponding sides.

Are the Triangles Similar? No.
Explanation: See solution.

Practice makes perfect

Let's review the theorems that can help us prove that two triangles are similar.

  1. AA (Angle-Angle) ~ Postulate: If two angles of one triangle are congruent to two angles of another triangle, then the triangles are similar.
  2. SSS (Side-Side-Side) ~ Theorem: If the corresponding side lengths of two triangles are proportional, then the triangles are similar.
  3. SAS (Side-Angle-Side) ~ Theorem: If the lengths of two sides of one triangle are proportional to the lengths of two corresponding sides of another triangle and the included angles are congruent, then the triangles are similar.
We are asked to determine whether the given triangles are similar.

Notice that we are given the lengths of all of the sides in both triangles. Therefore, we can compare the ratios of the corresponding sides. To identify them we can use the side lengths.

Let's find and simplify the ratios! rccccc Shortest Sides: &JK/QR & = & 32/22 & = & 16/11 [0.8em] Longest Sides: &JL/PQ & = & 60/40 & = & 3/2 [0.8em] Remaining Sides: &LK/PR & = & 45/30 & = & 3/2 As we can see, only two of the ratios are equal. Therefore, the corresponding sides are not proportional and the given triangles are not similar.