Two similar triangles have areas in the ratio 4 : 9. The perimeter of the smaller triangle is 20 cm. What is the perimeter of the larger one?
Answer and explanation
Correct answer: C. 30 cm
- Step 1: The ratio of areas is the square of the ratio of lengths, so the ratio of lengths is . Step 2. Perimeters are lengths, so the larger perimeter is cm. Answer: 30 cm. Why not the others: 45 cm applies the area ratio to a length, cm uses the length ratio upside down, and 25 cm adds the difference to the perimeter.
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