Not here. It would resemble a chevron.
a right angle triangle.
yes it can be a circle has no straight sides, but is symmetrical
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.