# Math Vocab Words- Chapter 8

## 33 terms

### angle

figure formed by two rays with a common endpoint

### vertex

common endpoint of two rays

### acute angle

angle measure of less than 90 degrees

### right angle

the 90 degree angle between two perpendicular lines

### obtuse angle

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

### straight angle

an angle of 180 degrees

### congruent

Having the same size, shape, and measure

### vertical angle

either of two equal and opposite angles formed by the intersection of two straight lines

2 angles that have the same vertex and a common ray but no interior points in common

### complementary angle

two angles that add up to 90 degrees

### supplementary angle

two angles whose measures have a sum of 180 degrees

### point

an exact location

### line

a straight path that goes on forever in both directions

### plane

a flat surface that extends without end in all directions

### line segment

part of a line with two endpoints

### ray

a straight line extending from a point that goes on forever in one direction

### parallel lines

Lines in the same plane that do not intersect

### perpendicular lines

Two lines that intersect to form right angles

### skew lines

lines that lie in different planes. they are neither parallel or intersecting

### acute triangle

a triangle that has three acute angles

### obtuse triangle

a triangle with one obtuse angle

### right triangle

a triangle with one right angle

a plane figure with 4 sides and 4 angles

### parallelogram

a quadrilateral whose opposite sides are both parallel and equal in length

### rectangle

a parallelogram with four right angles

### rhombus

a parallelogram with 4 congruent sides

### square

a rectangle with four equal sides and four right angles

### trapezoid

a quadrilateral with two parallel sides

### line symmetry

a property that a shape can have. means that when you fold the figure in half , the 2 halves match exactly.

### line of symmetry

a line that divides a figure into 2 halves that match exactly when the figure is folded on that line

### equilateral triangle

a triangle with three equal sides

### isosceles triangle

a triangle with two congruent sides

### scalene triangle

a triangle with no congruent sides