ACT® Math: Geometry Terms and Formulas

A set of vocabulary flashcards covering geometric relationship terms and definitions based on the ACT® Math study materials.

Bisect

To cut in two equal parts.

Equidistant

Being the same distance from two points or lines.

Congruent

Having the same shape and size. Congruent angles have the same measure. Congruent figures have equal side lengths and equal angle measures.

Parallel

Lines in the same plane that never intersect, no matter how far they are extended.

Perpendicular

Lines, segments, or rays that intersect at a $90^{\circ}$ (right) angle.

Surface Area

A measure of the total area of all the faces (outer surfaces) of a three-dimensional solid. You can find the surface area by adding all the areas of the faces.

Perimeter

The distance around a two-dimensional figure; you can find the perimeter of any figure by adding all the side lengths.

Hypotenuse

The longest side of a right triangle, located opposite the right angle.