Math VocabularyUnit 5 1

GeometryBy Jim Auld

Angles• Right

90°

Angles• Acute

An angle measuring less than 90°

Angles• Obtuse

An angle measuring more than 90° and less than 180°

TrianglesThe Sum of all the angles = 180°• Equilateral Triangle

A triangle with 3 congruent sides

TrianglesThe Sum of all the angles = 180°• Scalene Triangle

A triangle with NO congruent sides

TrianglesThe Sum of all the angles = 180°• Isosceles Triangle

A triangle with two congruent sides

TrianglesThe Sum of all the angles = 180°• Right Triangle

A triangle with one right angle (90°)

QuadrilateralsThe Sum of all the angles = 360°

• A four-sided polygon

Quadrilaterals The Sum of all the angles = 360°• Parallel

Two Lines that never intersect

Quadrilaterals The Sum of all the angles = 360°• Rectangle

2 parallel sides4 Right Angles

Quadrilaterals The Sum of all the angles = 360°• Square

2 Parallel sides4 Right Angles4 Equal sides

Quadrilaterals The Sum of all the angles = 360°• Rhombus

A parallelogram whose four sides are congruent and whose opposite angles are congruent

Quadrilaterals The Sum of all the angles = 360°• Trapezoid

A quadrilateral with exactly one pair of parallel sides

Quadrilaterals

• ParallelogramA quadrilateral with

opposite sides are parallel and congruent

Regular Polygons

• A polygon with all sides and all angles equal

Regular Polygons

• PentagonA five-sided polygon. The sum of the angles of

a pentagon is 540 degrees.

Regular Polygons

• HexagonA six-sided polygon. The sum of the angles

of a hexagon is 720 degrees.

Regular Polygons

• HeptagonA seven-sided

polygon. The sum of the angles

of a hexagon is 900 degrees.

Regular Polygons

• OctagonAn eight-sided polygon. The sum of the angles of

an octagon is 1080 degrees.

Regular Polygons

• DecagonA ten-sided polygon. The sum of the angles of

a decagon is 1440 degrees.

Regular Polygons

• Convex A figure is convex if every line segment drawn between any two points inside the figure lies entirely inside the figure.

Math VocabularyUnit 5 2

GeometryBy Jim Auld

Investigation 2

• Perimeter The perimeter of a polygon is the distance around the outside of the polygonL + L + W + W = P

Investigation 2

• Area The number of square units it takes to completely fill a polygon.

L x W = A

Investigation 2

• Dimension The measurement of a polygon. Example: Length, Width or Height.

Investigation 2

• Similar Polygons that have the same shape, not necessarily the same size they are similar.