1. Bell Ringer

2. Area of a Triangle
Chapter 13.2

3. Triangles
A triangle is the simplest closed three-sided geometric figure.
How many line segments, angles, and vertices are needed to form a triangle?
To form a triangle, three line segments, three angles, and three vertices are needed.

5. Triangles are classified by their side lengths or by their angle measures.
The root word “equi” means “equal,” and the root word “lateral” means “side.”
An equilateral triangle is a triangle with all sides congruent.

6. An isosceles triangle is a triangle with at least two congruent sides.

7. A scalene triangle is a triangle with no congruent sides.

8. An acute triangle is a triangle that has three angles that each measure less than 90°.

9. A right triangle is a triangle that has a right angle.

10. An obtuse triangle is a triangle that has an angle measuring greater than 90°.

11. Finding the Area of a Triangle