Stefan is measuring the angles of a triangle. He measures the first angle and gets a measure of 80° What does he know for sure about the other two angles?

Question

Responses
A Their measures add up to 120°.Their measures add up to 120°.
B Their measures add up to 180°.Their measures add up to 180°.
C They are each 50°.They are each 50°.
D Their measures add up to 100°.

Answer 1

B Their measures add up to 180°. This is because the angles of a triangle always add up to 180°.