What shape has three right angles?

Answer 1

I will rephrase your question as "What shape has only three right angles?" A shape is a 2D drawing that encloses some space. The sum of the angles must exceed 270 degrees. A rectangle is out of the question as it has four right angles. But a 5 sided shape with unequal sides (irregular pentagon) or higher number of sides is fine. I wish Wikipedia would let draw on these answers, because I could draw hundreds of shapes with three right angles. When we talk of shapes, the most regular shapes come to mind, triangles, squares, pentagons, etc. But you did not spcify that my shape had to have straight sides. Imagine, for example, a circle which I will break at three places and insert right angles. Weird, but it does have three right angles. Do the right angles have to face in towards the center? I could even draw a more bizarre shape with with three right angles facing out, connected by curved lines.

Answer 2

On a sphere you can draw a triangle with three right angles. .

At the North pole , zero meridian and its right angle 90 oW merdian.

Draw these meridians to the Equator, and you will find they both meet the Equator at 90 o (degrees).