A triangle is considered to be an isosceles triangle if it has two equal sides.Here is a list of a few points that should be remembered while studying the perimeter of an isosceles triangle: Important Notes on Perimeter of Isosceles Triangle It should be noted that the two congruent angles in the isosceles right triangle measure 45° each. When the hypotenuse is given: Referring to the explanation given above, if the hypotenuse (h) is given, then the perimeter of an isosceles right triangle will be (P) = h + 2(h/√2) = h + √2h = h(1 + √2).When the length of the equal side is given: Referring to the explanation given above, if the length (l) is given, then the perimeter of an isosceles right triangle will be (P) = 2l + (√2)l = (2 + √2)l.These values can be substituted with each other if one of them is not known. This means h = √2 × l, which can also be written as: l = h/√2. If we apply the Pythagoras theorem in the figure, we get h = √(l 2+ l 2) = √2 × l. Now, let us find the perimeter of an isosceles right triangle in 2 different scenarios given below. Observe the following figure to understand the dimensions and the formula of an isosceles right triangle.Īs given in the figure, the perimeter of an isosceles right triangle is P = h + 2l. If the length of the hypotenuse is 'h' units and the lengths of the other two sides are 'l', then the perimeter of an isosceles right triangle would be: Perimeter of isosceles right triangle = h + l + l. Since it is a right-angled triangle, one of its sides is the hypotenuse and the other two sides are equal. The perimeter of an isosceles right-angled triangle can be found by adding the length of all its three sides.

Isosceles triangle sides ratio