How many sides does a rectangle have?
A rectangle is a four-sided shape whose corners are all ninety-degree angles. Each side of a rectangle is the same length as the one opposite to it. 长方形
Knowledge of "rectangle"
In Euclidean plane geometry, a rectangle is a quadrilateral with four right angles. It can also be defined as an equiangular quadrilateral, since equiangular means that all of its angles are equal (360°/4 = 90°). It can also be defined as a parallelogram containing a right angle.