a right angle triangle.
A right triangle has three sides and one right angle.
A right angle triangle
A Triangle~!
In plane geometry, a shape with four sides, two of which are parallel and have the same length, cannot have a reflex angle.
a right angle triangle.
A right triangle has three sides and one right angle.
A right angle triangle
A right angle triangle
A right-angle triangle.
rectangle
A square and a rectangle.
A Triangle~!
a triangle
A rectangle or a square: both have four sides and a right-angle of 90 degrees forming the four corners.
a right triangle
A right angled triangle.