math vocabulary


the size of a surface


the distance around a two-dimensional shape.

exterior angle

the angle between any side of a shape, and a line extended from the next side.


where the polygon grows or shrinks but keeps the same overall shape.

scale factor

a number which scales, or multiplies, some quantity.

Corresponding Angles

When two lines are crossed by another line

Line of Symmetry

does not have to be up-down or left-right, it can be in any direction.

acute angle

is less than 90°

Obtuse Angle

is more than 90° but less than 180°


is the distance around a two-dimensional shape.

Vertical Angles

the angles opposite each other when two lines cross.


If one shape can become another using Turns, Flips and/or Slides, then the shapes are Congruent


is a 4-sided flat shape with straight sides that has a pair of opposite sides parallel


The distance from the center to the edge of a circle

It is half of the circle's diameter.


A straight line going through the center of a circle connecting two points on the circumference

Surface Area

The total area of the surface of a three-dimensional object


The amount of 3-dimensional space an object occupies. Capacity.