Advanced MathHardWidth of a rectangle from its diagonal
Advanced Math practice question
A rectangle's length is 3 units more than its width, and its diagonal is 15 units long. What is the width of the rectangle?
Answer: 9
w² + (w + 3)² = 225 gives 2w² + 6w − 216 = 0, or w² + 3w − 108 = (w + 12)(w − 9) = 0, so w = 9.
Common wrong answers
- If you answered 12
- 12 is the length.
- If you answered 15
- 15 is the diagonal.
- If you answered -12
- −12 is the negative root.
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