why do triangle angles always sum to 180°?. in this lesson you will learn about the interior angles...
TRANSCRIPT
Why do triangle angles always sum to 180°?
In this lesson you will learn about the interior angles of triangles by looking at their
properties.
Let’s Review
The three angles of a triangle always sum to 180°.
98 + 42 + 40 = 18084 + 69 + 27 = 180111 + 46+ 23 = 180
90 + 68 + 22 = 180
Let’s Review
A line that passes through parallel lines is called a transversal.
Let’s Review
Transversals create special angle properties.
Alternate Exterior AnglesCorresponding AnglesAlternate Interior Angles
Core Lesson
Triangles share many of these angle relationships.
1
1 2
3
3
Core Lesson
Find the missing angle measurement.
x
89 + 68 = 157
180-157 = 23
x = 23°
In this lesson you have learned about the interior angles of triangles by looking at their
properties.