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.

   Bo sees triangle A on a sail. A has a 31° angle and a 54° angle. The sketch writes 180° beside the triangle. What is A's third angle?

   95
3. 3.

   Esme sees triangle A on a roof. A has a 66° angle and a 29° angle. The sketch writes 180° beside the triangle. What is A's third angle?

   85
4. 4.

   Jun sees triangle A on a kite wing. A has a 77° angle and a 48° angle. The sketch writes 180° beside the triangle. What is A's third angle?

   55
5. 5.

   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
6. 6.

   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
7. 7.

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

   • Yes: all three angles match, so they are similar
   • Not enough to tell: we need the side lengths first
   • No: B is much bigger than A, so they are not similar
   • No: the lists start with 40° and 75°, so they are not similar
8. 8.

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

   • Yes: all three angles match, so they are similar
   • Not enough to tell: we need the side lengths first
   • No: the lists start with 35° and 50°, so they are not similar
   • No: B is much bigger than A, so they are not similar
9. 9.

   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
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 S
    • corner Q
    • corner H