Analyze Relationships---One angle of a triangle measures 120°. The other two angles are congruent. Write and solve an equation to find the measure of the congruent angles.

First, you should know that the 3 angles of any triangle add to equal 180 °.

So, it's given that one angle is 120 ° wide and the others are congruent. Since they are congruent, we can assign the same variable to each. Let's say each one equals x. So,

120 ° + the first unknown angle + the second unknown angle = 180°

120° + x + x = 180°

120° + 2x = 180°

Now we just have to solve for x to find the angle measurement for each of the two missing angles.

2x = 180° - 120°

2x = 60°

x = 60°/2

x = 30°