A square is a plane geometric figure having 4 equal sides and 4 right angles.
Yes. It is a quadrilateral with right angles and opposite sides equal.
An acute triangle.
a circle
A rhombus is a geometric figure having four sides of equal length. If all the angles inside the rhombus are right angles (90o), then the rhombus is a square.
No. The term is actually applied to a different geometric shape: one with adjacent pairs of equal angles (truncated isoceles triangle). There is such a geometric shape as a "right trapezium" (US) and a "right trapezoid" with adjacent right angles (e.g. "the doorstop" or truncated rectangle that includes a square or rectangular segment).
All triangles that are not right triangles.
An obtuse triangle can have no right angles, and has two equal angles.
right
A right triangle can have 2 equal angles if they are each 45° (any other right triangle will have no equal angles)
Rectangle, octagon, hectagon, square...
Circle, cone, cylinder, sphere and equilateral triangle for example.