That the sum measures of the interior angles of a triangle is 180

The Triangle sum theorem states that the sum measures of the interior angles of a triangle is 180 degree

Solution:

We know that,  

The Triangle Sum Theorem states that if you add all three interior angles, those are the angles inside the triangle, they would always add up to 180 degrees.

It is easy to remember that we add the three angle measurements to get 180 degrees because of the word sum in the name of the theorem. To make it short and sweet:

Consider a triangle with interior angles a, b, and c. Then we can say,

The Triangle Sum Theorem is also called the Triangle Angle Sum Theorem or Angle Sum Theorem

12

step-by-step explanation:

a triangle's   full angle is 180 degrees so 180 - 156 = 24. 24/2=12