Question

How do you find the measure of this angle ?

Answer 1

The lines through the sides in the circle indicate that the three sides are all of the same length, and therefore share the same angle.

A shape inside a circle will always have its angles equal 360, so you can find the individual angle with the following equation:

$120 + 3x = 360$

Subtract 120 from both sides.

$3x = 240$

Divide both sides by 3.

$x = 80$

mBC's angle is 80 degrees.