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.

   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
2. 2.

   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
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.

   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
5. 5.

   Pia compares a small sail A and a big sail 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
   • Not enough to tell: we need the side lengths first
6. 6.

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

   • Not enough to tell: we need the side lengths first
   • No: the lists start with 40° and 75°, so they are not similar
   • No: B is much bigger than A, so they are not similar
   • Yes: all three angles match, so they are similar
7. 7.

   Tala compares a small tent A and a big tent 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
   • No: the lists start with 30° and 80°, so they are not similar
8. 8.

   Luz labels the corners of two similar sails. Triangle SUV is the small one and triangle WYC is the big one. Which corner of WYC matches corner V?

   • corner Y
   • corner C
   • corner W
9. 9.

   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 Q
   • corner S
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