In an isosceles triangle, one of the sides is 10cm. and the other is 12cm larger than her, find the perimeter of the triangle.


1) From the condition we know that one of the sides in an isosceles triangle is 10 cm.Since the other side is 12 cm larger, then we find the length of this side:

10 cm + 12 cm = 22 cm.

2) Since the triangle is isosceles, then the two sides are equal.

Find the perimeter of the triangle:

P = 2 a + b, where

P is the perimeter of the triangle;

a – the thigh of the triangle;

b is the base of the triangle.


P = 2 * 10 cm + 22 cm = 20 cm + 22 cm = 42 cm.

The perimeter of this isosceles triangle is 42 cm.

Answer: 42 cm.

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