a triangle
4
An equilateral triangle.
A triangle is the 2D name of a certain shape. A triangle has three sides and, in the case of a right angled triangle, has an angle of 90 degrees in one corner. There are many other names depending on the angles used.
An equilateral triangle.
A cyclic kite. A kite is cyclic if it has only two right angles.
square
A square
3d not = to 2d
a square
No
rhombus