SOLUTION
From the diagram below,
Triangle A is right isosceles, since two angles are equal, two sides are equal, and there is a right-angle (90 degrees angle) present.
Triangle B is obtuse scalene, since none of the sides are equal, and one of the angles is greater than 90 degrees.
Triangle C is acute scalene, since none of the sides are equal, and all the angles are less than 90 degrees.
Triangle D is acute isosceles, since two angles and two sides are equal, and all the angles are less than 90 degrees.
