Multiple choice

ΔABC and ΔDEF are similar triangles and their areas be respectively 64 cm2 and 121 cm2. If EF = 15.4 cm, BC is-

  1. 12.3 cm

  2. 11.2 cm

  3. 12.1 cm

  4. 11.0 cm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For similar triangles, (side ratio)² = (area ratio). Area ratio = 64/121, so side ratio = √(64/121) = 8/11. This means corresponding sides are in proportion 8:11. EF is from the larger triangle (area 121), BC from the smaller (area 64). So BC/EF = 8/11, giving BC = 15.4 × 8/11 = 11.2 cm.

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