# Chap. 1 vocab side 2

## 17 terms

### legs

the two congruent sides of an isosceles triangle or the two sides that form a right angle

### line segment

a set of points consisting of two points on a line, called endpoints, and all the points on the line between the endopints

### midpoint

a point of that line segment that divides the segment into two congruent segments

### non-collinear set of points

a set of three or more points that do not all lie on the same straight line

### obtuse angle

an angle whose degree measure is greater than 90 and less than 180

### obtuse triangle

a triangle that has and obtuse angle

### opposite rays

two rays of the same line with a common endpoint and no other points in common

### perpendicular lines

two lines that intersect to form right angles

### polygon

a closed figure in a plane that is the union of line segments such that the segments intersect only at their endpoints and no segments sharing a common endpoint are collinear

### ray

a part of a line that consists of a point on the, called an endpoint, and all the the points on one side of the endpoint

### right angle

an angle whose degree measure is 90

### right triangle

a triangle that has a right angle

### scalene triangle

a triangle that has no congruent sides

### striaght angle

an angle that is the union of opposite rays and whose degree measure is 180

### triangle

a polygon that has exactly three sides

### undefined terms

their meaning is accepted without a definition; line, point, plane

### vertex angle

the angle opposite the base in an isosceles triangle