Angles g and h are supplementary and congruent. if g and h are alternate interior angles, what is the measure of each angle?

Supplementary means that they add up to 180.  Congruent means they are the same angle.  90 degrees for both

Lines that intersect at one point

The sum of the angles in a triangle is 180°. this is called the angle-sum property.the sum of the lengths of any two sides of a triangle is greater than the length of the third side. similarly, the difference between the lengths of any two sides of a triangle is less than the length of the third side.the side opposite to the largest angle is the longest side of the triangle and the side opposite to the smallest angle is the shortest side of the triangle.