Final answer:
In isosceles triangles, the base angles are congruent and in equilateral triangles, all three angles are congruent. The hypotenuse is the longest side of a right triangle and the altitude is a line segment drawn from a vertex perpendicular to the opposite side.
Step-by-step explanation:
For part A) Base angles, in isosceles triangles, the base angles are always congruent. So if we know one of the base angles, we can find the other base angle by subtracting it from 180 degrees and then dividing by 2.
For part B) Vertex angles, in equilateral triangles, all three angles are congruent and each angle measures 60 degrees.
For part C) Hypotenuse, the hypotenuse is the longest side of a right triangle and it is always opposite the right angle.
For part D) Altitude, the altitude of a triangle is a line segment drawn from a vertex perpendicular to the opposite side. Altitudes can be found using the Pythagorean theorem or by using the formula A = (1/2) * base * height, where base is the length of the side of the triangle and height is the length of the altitude.