Answer:
Part 1) The sum of the interior angles is equal to 180 degrees
Part 2) The measure of angle N is ∠N=60°
Part 3) The measure of angle M is ∠M=120°
Part 4) The sum of the the exterior angles is 360°
Explanation:
Part 1) What is the sum of the interior angles of the equilateral triangle?
we know that
The sum of the interior angles of any triangle must be equal to 180 degrees
Part 2) What is the measure of ∠N?
we know that
An equilateral triangle has three equal sides and three equal internal angles ( each internal angle measure 60 degrees)
so
In this problem
∠N=60°
Part 3) What is the measure of ∠M? Explain your reasoning.
we know that
∠M+∠N=180° -----> by supplementary angles (linear pair)
we have
∠N=60°
substitute
∠M+60°=180°
∠M=180°-60°=120°
Part 4) What is the sum of the exterior angles of the equilateral triangle ∠M + ∠R + ∠X?
we know that
The sum of the the exterior angles of any polygon is equal to 360 degrees
In this problem
we have
∠M=∠R=∠X=120°
so
∠M+∠R+∠X=120°+120°+120°=360°