An isosceles triangle has two angles that measure 75°. What is the measure of the third angle of the triangle?
A. 30°
B. 40°
C. 75°
D. 90°
I really don't know which one...

Question

An isosceles triangle has two angles that measure 75°. What is the measure of the third angle of the triangle?
A. 30°
B. 40°
C. 75°
D. 90°
I really don't know which one...

butterflydreamer · Answer

Do you know what the angle sum of a triangle is? :)

spacemountain · Answer

Not really..

butterflydreamer · Answer

Okay, well the angle sum of a triangle = 180 degrees.
Therefore this means the sum of all three angles in a triangle = 180 degrees.
Since they've told us that your triangle is an isosceles, it means that the triangle has two base angles which equal to 75.

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So, since you have two angles which are 75 degrees each, to find the third angle you will do 180 - 75 - 75 = ?