Are these triangles similar? (angle-angle)

Answer Key - Grade 8 Math Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. 1.

   Ari sees triangle A on a tent flap. A has a 42° angle and a 63° angle. The sketch writes 180° beside the triangle. What is A's third angle?

   75
2. 2.

   Kira enlarges a small sail A into a big sail B. The scale factor from A to B is 3. How many cm long is B's side across the 40° angle?

   54
3. 3.

   Noah enlarges a small tent front A into a big tent front B. The scale factor from A to B is 4. How many cm long is B's side across the 55° angle?

   48
4. 4.

   Pia compares a small sail A and a big sail B. Are the two triangles similar?

   • Not enough to tell: we need the side lengths first
   • Yes: all three angles match, so they are similar
   • No: B is much bigger than A, so they are not similar
5. 5.

   Ren compares a small roof A and a big roof B. Are the two triangles similar?

   • No: the lists start with 40° and 75°, so they are not similar
   • Not enough to tell: we need the side lengths first
   • No: B is much bigger than A, so they are not similar
   • Yes: all three angles match, so they are similar
6. 6.

   Tala compares a small tent A and a big tent B. Are the two triangles similar?

   • No: B is much bigger than A, so they are not similar
   • Yes: all three angles match, so they are similar
   • No: the lists start with 30° and 80°, so they are not similar
   • Not enough to tell: we need the side lengths first
7. 7.

   Zee compares two kite wings, A and B. Are the two triangles similar?

   • Yes: both have a 40° angle, so they are similar
   • No: the angles do not all match, so they are not similar
   • Not enough to tell: we need the side lengths first
8. 8.

   Bo compares two triangle warning signs, A and B. Are the two triangles similar?

   • No: the angles do not all match, so they are not similar
   • Yes: both have a 25° angle, so they are similar
   • Not enough to tell: we need the side lengths first
9. 9.

   Esme compares a small paper pennant A and a big paper pennant B. Are the two triangles similar?

   • No: B is much bigger than A, so they are not similar
   • No: the lists start with 35° and 50°, so they are not similar
   • Not enough to tell: we need the side lengths first
   • Yes: all three angles match, so they are similar
10. 10.

    Noah labels the corners of two similar kites. Triangle WYC is the small one and triangle DFG is the big one. Which corner of DFG matches corner Y?

    • corner D
    • corner G
    • corner F