Intro to triangle angle sum theorem and classifying triangles.

4. 80 90 100
70 110
60 120
100 90 80
50 110 70 130
120 60
40 130 50 140
140 0° 40
30 150
150 30
20 160
160 20
10 170
170 10
0 180 0 180
115°
37°
28°