This document defines and describes different types of angles and triangles. It explains that angles are formed by two rays sharing a common endpoint, and defines acute, right, and obtuse angles. It then defines equilateral, isosceles, right, and scalene triangles based on their side lengths and angle measures. Examples are provided to illustrate each triangle type.

1. Angles and
Triangles

2. Angles
A shape formed by two rays sharing a common endpoint; contains two
rays and a vertex
ray
ray
vertex
ray—has one endpoint and
goes infinitely in one direction
vertex—point common to two
rays of a triangle or two sides
of a polygon

3. Types of Angles
Acute angle: An angle whose measure is greater than zero degrees and
less than 90 degrees
Which angles are not acute?
1
2
3
4
5

4. Types of Angles
Right angle: Angle that measures 90 degrees
Which angle is a right angle?
1
2
3
4
5

5. Types of Angles
Obtuse angle: One angle measures greater than 90 degrees and less
than 180 degrees
Which angle is an obtuse angle?
1
2
3
4
5

6. Straight Angle
Straight angle: A line that goes infinitely in both directions and
measures 180 degrees
Which is not a straight angle?
1
2
This is a ray. It only
goes in one direction.

7. Types of Triangles
Equilateral triangle: A triangle with three congruent (equal) sides and
three equal angles
These marks indicate equality.

8. Types of Triangles
Isosceles triangle: A triangle with at least two congruent (equal) sides

9. Types of Triangles
Right triangle: Has only one right angle (90 degrees)
This box indicates a right
angle or a 90-degree angle.

10. Types of Triangles
Scalene triangle: A triangle that has no congruent (equal) sides

11. Types of Triangles
Name each type of triangle
1
2
3
4

12. Types of Triangles
Name each type of triangle
1
2
3
4
Equilateral
Right
Isosceles
Scalene