Created by Mrs. Leslie

Unit 3 Geometry Vocabulary

A count or list, one-by-one, of every member of a population; a census may also be used to collect information about the population, such as age and occupation.

census

An angle whose measure is greater than 0˚ and less than 90˚.

acute angle

An angle whose measure is greater than 90˚ and less than 180˚.

obtuse angle

An angle that measures 90˚.

right angle

An angle that measures 180˚.

straight angle

An angle whose measure is greater than 180˚ and less than 360˚. When the reflex angle is supposed to be measured, an arc will be shown on the angle.

reflex angle

The radius of a circle is any line segment from the center of the circle to any point on the circle.

radius

The diameter of a circle is any line segment that passes through the center of the circle and has it’s endpoints on the circle.

diameter

When two lines intersect, the measures of the angles opposite each other are equal and are called vertical or opposite angles.

vertical or opposite angle

Angles that are next to each other and have a common side.

adjacent angles

The two angles above are next to each other and share a common side (shown in red).

A triangle that has three sides that are the same length. Each angle measures 60˚.

equilateral triangle

A triangle that has two sides that are the same length.

Isosceles triangle

A triangle that has no sides that are the same length.

scalene triangle

The name given to figures that are the same size and same shape.

congruent

A polygon whose sides are the same length and their angle measures are equal.

regular polygon

An arrangement of repeated, closed shapes that cover a surface so no shapes overlap and no gaps exist between shapes.

tesselation

The point at where the vertices meet in a tesselation.

tesselation vertex