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.

   Milo enlarges a small roof A into a big roof B. The scale factor from A to B is 2. How many cm long is B's side across the 25° angle?

   28
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.

   Tala compares a small tent A and a big tent B. Are the two triangles 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
   • No: B is much bigger than A, so they are not similar
6. 6.

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

   • Not enough to tell: we need the side lengths first
   • No: the angles do not all match, so they are not similar
   • Yes: both have a 40° angle, so they are similar
7. 7.

   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
   • Yes: all three angles match, so they are similar
   • Not enough to tell: we need the side lengths first
8. 8.

   Jun labels the corners of two similar triangle warning signs. Triangle CDF is the small one and triangle UVW is the big one. Which corner of UVW matches corner C?

   • corner U
   • corner W
   • corner V
9. 9.

   Kira labels the corners of two similar tents. Triangle GHQ is the small one and triangle SUY is the big one. Which corner of SUY matches corner H?

   • corner S
   • corner U
   • corner Y
10. 10.

    Milo labels the corners of two similar roofs. Triangle DFG is the small one and triangle HQS is the big one. Which corner of HQS matches corner G?

    • corner H
    • corner S
    • corner Q