Multiple choice

The perimeters of two similar triangles XYZ and MNO are 78 cm and 46.8 cm, respectively. If MN=11.7 cm, then the length of XY is:

  1. 19.5 cm

  2. 23.4 cm

  3. 24 cm

  4. 20 cm
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A Correct answer
Explanation

For similar triangles, ratio of perimeters = ratio of corresponding sides. Ratio = 78/46.8 = 780/468 = 5/3. So XY/MN = 5/3. XY/11.7 = 5/3. XY = (5/3) × 11.7 = 5 × 3.9 = 19.5 cm.

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