right triangle 
noun North American
A right-angled triangle.To fit the National Gallery's East Building on a trapezoid-shaped site, architect I.M. Pei based his design on a division of a trapezoid into an isosceles triangle and a smaller right triangle....
- The base of the wedge is an isosceles right triangle in a vertical plane.
- Indeed, if there is one thing that someone might remember from grade school mathematics, it's the fact that ‘the square of the hypotenuse of a right triangle is equal to the sum of the squares of the two adjacent sides.’