First Triangle
Angles are all equal 60° because 180 - 120 = 60 and angle C is congruent to angle B because it is an isosceles triangle based on the markings and the third angle must be 60° because 60 + 60 + 60 = 180. Since all the angles equal 60° the triangle is and equilateral triangle.
Second Triangle
The triangle is an isosceles triangle based on the markings. Amusing that angle A is a right angle (by looks) angles B and C equal 45° and angle A equals 90° making the triangle a 45°-45°-90° Special Right Triangle.
Hope this helps! ;)
