A circle. One side, zero angles. Also a line as it is a 1-dimensional shape.
A right trapezoid.
They are said to be similar if they have the same angles but different lengths
A trapezoid can have 2 right angles and 1 pair of opposite parallel sides of different lengths. The 4 interior angles will add up to 360 degrees.
A cuboid is a three dimensional shape, like a cube but with sides of different lengths. A number cannot have a cuboid.
There is no standard formula. The answer will depend on the compound shape and also on which of the lengths (or angles) are known.