Geometry Terms

Acute Angle

• An angle that measures less than 90 degrees.

• An angle that measures exactly 90 degrees.

• An angle that measures more than 90 degrees but less than 180 degrees.

• An angle that measures exactly 180 degrees.

Equilateral Triangle

• A triangle with all three sides of equal length.

• A triangle with one angle greater than 90 degrees.

• A triangle with two sides of equal length.

• A triangle where all angles are acute.

Right Triangle

• A triangle in which one interior angle is a right angle (exactly 90 degrees).

• A triangle in which one interior angle is a right angle (exactly 90 degrees).

• A triangle with two equal sides and one angle greater than 90 degrees.

• A triangle that has no equal sides.

Perimeter

• The distance around the outside of a shape.

• The area inside a shape.

• The length of the longest side of a shape.

• The sum of all angles in a shape.

Isosceles Triangle

• A triangle with two sides of equal length.

• A triangle with all sides of different lengths.

• A triangle with one right angle.

• A triangle with three equal sides.

Volume

• The amount of space an object takes up in three dimensions. Volume is measured in cubic units, such as cubic centimeters (cm3) or cubic meters (m3).

• The weight of an object in grams.

• The surface area of an object in square units.

• The density of an object measured in kilograms per cubic meter.

Congruent

• Identical shape and size.

• Similar shape but different size.

• Different shape but same size.

• Completely unrelated shapes.

Obtuse Triangle

• A triangle in which one interior angle is obtuse (greater than 90 degrees).

• A triangle in which one interior angle is obtuse (greater than 90 degrees).

• A triangle that has one right angle (exactly 90 degrees).

• A triangle with all sides of equal length.

Right Angle

• An angle that measures exactly 90 degrees.

• An angle that measures exactly 45 degrees.

• An angle that measures exactly 180 degrees.

• An angle that measures less than 90 degrees.

Width

• The distance from side to side.

• The distance from top to bottom.

• The distance from front to back.

• The distance from one corner to another.