Unit 5 · Geometry
Same Perimeter Puzzle — 9 cm Rhombus, Find the Width!
Lesson 3 of 6
About this lesson
A rectangle and a rhombus share the same perimeter. The rhombus side is 9 cm → perimeter 36 cm. The rectangle length is 14 cm → width = ? The classic trap is option D (22 cm): students who compute 36 − 14 = 22 forget that a rectangle has TWO lengths, so you must halve the perimeter first: 36 ÷ 2 = 18, then subtract 14 to get 4.
Chapters
Question
A rectangle and a rhombus have the same perimeter.
Joel measures one edge of the rhombus and finds that it is 9 centimetres long.
Jenna measures the length of the rectangle and finds that it is 14 centimetres long.
What is the width of the rectangle?
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