Answer:
100
Step-by-step explanation:
Remark
If two opposite arcs are given by being opposite vertically opposite angles, then the value of both the vertically opposite angles are equal to
Vertically opposite angle = 1/2 (arc1 + arc2)
Givens
Arc1 = 60
Arc2 = 100
Solution
The red dot angle = 1/2 (60 + 100)
The red dot angle = 1/2(160)
The red dot angle = 80
Because the red dot angle and <3 are on the same line with the same common point, they are supplementary.
<3 and red dot = 180
<3 + 80 = 180 Subtract 80 from both sides
<3 = 180 - 80
<3 = 100
