1. Angle Measure in Triangles
Journal Notes

2. Sum of Angles in a Triangle
The sum of angles in a triangle are always 180.
This works for all triangles.

3. Find the missing angle
A isosceles triangle has two angles of 65. What is the missing angle?
Step 1- write an equation filling in the original triangle angle equation of **A1+A2+A3=180
You know two angles so fill in two ** A3=180
Step 2-Simplify 130+X=180
Solve using inverse operations X=
X=50
CHECK! Add ALL THREE angles to see if you get 180

4. You try
A triangle has one angle measure of 100 and one angle measure of 50. What is the missing angle measure?

5. Angles in Equilateral Triangles
An equilateral triangle has all equal sides AND all equal angles.
The equation to find the angle for equilateral triangle is 3x=180
Inverse operations to solve for x
X=180/3
X=60
Each angle in an equilateral triangle is 60