Which pairs of triangles MUST be similar?
a. Triangles 1 and 2 each have one angle in common.
b. Triangles 3 and 4 are both isosceles. They each have a 60 degrees angle.
c. Triangles 5 has a 20 degrees angle and a 100 degrees angle. Triangle has a 20 degrees angle and a 60 degrees angle.
d. Triangle 7 has a 70 degrees angle and a 25 degrees angle. Triangle 8 has a 50 degrees angle and a 105 degrees angle.
