AlgebraHardFirst side of a triangle from its perimeter
Algebra practice question
A triangle has a perimeter of 54 centimetres. Its second side is twice as long as its first side, and its third side is 6 centimetres longer than its first side. How long, in centimetres, is the first side?
Answer: 12
x + 2x + (x + 6) = 54 gives 4x = 48, so x = 12.
Common wrong answers
- If you answered 18
- 18 is the third side.
- If you answered 24
- 24 is the second side.
- If you answered 13.5
- 13.5 divides 54 by 4 without subtracting the 6.
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