SOLUTION: 1. An isosceles triangle has a perimeter of 55 cm. Find the length of one of the equal sides if the third side is 15 cm long.

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Question 64593: 1. An isosceles triangle has a perimeter of 55 cm. Find the length of one of the equal sides if the third side is 15 cm long.



Answer by 303795(602) About Me  (Show Source):
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The perimeter is found by adding the lengths of the three sides. Given that it is an isoceles triangle then two sides have the same length.
x + x + 15 = 55
Subtract 15 from each side
x + x + 15 - 15 = 55 - 15
x + x = 40
If 2x = 40 then x = 20
The triangle has side lengths of 15 cm, 20 cm and 20 cm.