Which pair of triangles must be similar?

a.) triangles 1 and 2 they each have a 40 degree angle.
b.) triangle 7 has a 40 degree angle and a 35 degree angle. triangle 8 has a 40 degree angle and a 105 degree angle.
c.) triangle 5 has a 25 degree angle and a 75 degree angle. triangle 6 has a 25 degree angle and a 70 degree angle.

b.) Triangle 7 has a 40 degree angle and a 35 degree angle. Triangle 8 has a 40 degree angle and a 105 degree angle.

Step-by-step explanation:

b.) triangle 7's 3 angles: 40° , 35° and 180° - 40° - 35° = 105°

    triangle 8: 40° , 105° and 180° - 40° - 105° = 35°

they have all 3 corresponding angles congruent, triangle and triangle 8 is similar (AAA)

1/4 because there is 4 grades.