玄数

• Sloping or joining something at an angle that is not a right angle.
• Neither perpendicular nor parallel to another line or plane.

oblong   长方形的,矩形的；椭圆形的
Having the shape of or resembling a rectangle or ellipse.

obtuse angle   钝角
An angle greater than 90° and less than 180°.

obtuse triangle   钝角三角形
A triangle with one obtuse angle.


octagon   八边形
A polygon with eight sides and eight angles.

octahedron   八面体
A polyhedron with eight faces.

odd   奇数的

• Not divisible by two.
• Changing sign but not absolute value when the sign of the independent variable is changed, as in y = x³.

odd number   奇数
Designating an integer not divisible by two, such as 1, 3, and 5.