A parallelogram has sides 20 cm and 12 cm. The distance between the two longer sides is 9 cm. What is the distance between the two shorter sides?

5.4 cmCorrect answerYour answer7.5 cmCorrect answerYour answer9 cmCorrect answerYour answer15 cmCorrect answerYour answer

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CorrectNot quiteAnswer D

Correct answer: D

Area = longer side × distance between the longer sides = $20 \times 9 = 180$ cm².
The same area = shorter side × distance between the shorter sides, so the distance = $180 \div 12 = 15$ cm.

Worth noting

5.4 cm comes from pairing the base with the wrong height $(12 \times 9 \div 20)$ . The shorter sides are further apart, because the same area is spread over a shorter base.

Concept: Area of a parallelogram with either pair of sides as base
Typical timeTypical: 70 s
Your timeYours: —

The rule this testsPerimeter and area

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Ten questions from Mensuration: Areas and Volumes, at your own pace.

A parallelogram has sides 20 cm and 12 cm. The distance between the two longer sides is 9 cm. What is the distance between the two shorter sides?

Explanation