Quadrilaterals （四边形）

1. Trapezoid梯形

1.1. • One pair of opposite sides parallel 一组对边平行

2. Rhombus 菱形

2.1. Opposite sides are parallel 对边平行

2.2. Diagonals are equal in length 对角线长相等

2.3. All four sides are equal 四边相等

2.4. Opposite angles are equal in magnitude 对角相等

2.5. Diagonals bisect each other at right angle 对角线互相垂直平分

2.6. Diagonals bisect the opposite right angles, as line of symmetry 对角线平分对角

3. Square 正方形

3.1. Opposite sides are parallel 对边平行

3.2. All four sides are equal in length 四边长相等

3.3. All four angles are right angles 四个内角都是直角

3.4. Diagonals bisect each other at right angles 对角线互相垂直平分

4. • Diagonals bisect each other 对角线互相平分

4.1. • Opposite sides are parallel 对边平行

5. The longer diagonal bisects the other diagonal at right angles 长对角线垂直平分另一条对角线

6. One diagonal is an axis of symmetry 一条对角线是对称轴

7. Two pairs of adjacent sides are equal in length 两组邻边相等

8. Parallelogram 平行四边形

8.1. • Opposite sides are parallel 对边平行

8.1.1. • Diagonals are equal in length 对角线长相等

8.2. • Opposite sides are equal in length 对边长相等

8.3. • Opposite angles are equal 对角相等

9. Rectangle 长方形

9.1. • Opposite sides are equal in length 对变长相等

10. Kite 风筝形

10.1. • All four interior angles are right angles 四个内角都是直角

10.2. One pair of equal opposite angles 一组对角相等

10.2.1. • Diagonals bisect each other 对角互相平分