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Isosceles Right Triangle


IsoscelesRightTriangle

An isosceles right triangle is a right triangle with the two legs (and their corresponding angles) equal. An isosceles right triangle therefore has angles of 45 degrees, 45 degrees, and 90 degrees. For an isosceles right triangle with equal legs of length a, the hypotenuse has length sqrt(2)a. The hypotenuse length for a=1 is called Pythagoras's constant.

Polyforms made up of isosceles right triangles are called polyaboloes.

The altitude from the right angle to the hypotenuse of an isosceles right triangle with equal legs of length a is

 h=1/2sqrt(2)a,
(1)

and the area is

A=1/2a^2
(2)
=h^2
(3)
=(3+2sqrt(2))r^2
(4)
=R^2,
(5)

where r is the inradius and R is the circumradius.

IsoscelesRightTriangleI
IsoscelesRightTriangleO

The inradius r and circumradius R are

r=1/2(2-sqrt(2))a
(6)
R=1/2sqrt(2)a.
(7)

Triangle line picking for points in an isosceles right triangle with edge lengths a, a, and sqrt(2)a gives a mean line segment length of

l^__(Delta(a,a,sqrt(2)a))=1/(30)[2+4sqrt(2)+(4+sqrt(2))sinh^(-1)1]a
(8)
=1/(60)(4+8sqrt(2)+sqrt(2)cosh^(-1)3+8sinh^(-1)1)a
(9)
=0.414293...a.
(10)

See also

30-60-90 Triangle, Isosceles Triangle, Polyabolo, Right Triangle

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Cite this as:

Weisstein, Eric W. "Isosceles Right Triangle." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/IsoscelesRightTriangle.html

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