Answer:
Step-by-step explanation:
because this is an isoscele triangle this means that the angles from the base are congruent what mean that than one angle has measure of 54 degree - given - so the second angle from the base has a measure of 54 degree too
we know that the sum of angles of a triangle is equal 180 degrees so the vertex angle has a measure of 180 -(54+54) = 180 -108 = 72 degrees
