Law of Cosines, and which law to use

Answer Key - Grade 10 Math Worksheet - Challenge Me

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

1. 1.

   Luz's triangle DFG has DF = 5 cm, DG = 7 cm and FG = 10 cm. FG is the longest side. What is ∠D, to the nearest tenth of a degree?

   111.8
2. 2.

   Noah's triangle DFG has DF = 8 cm, DG = 11 cm and FG = 16 cm. FG is the longest side. What is ∠D, to the nearest tenth of a degree?

   113.8
3. 3.

   Pia's triangle DFG has DF = 5 cm, DG = 8 cm and FG = 11 cm. FG is the longest side. What is ∠D, to the nearest tenth of a degree?

   113.6
4. 4.

   Tala's triangle DFG has DF = 10 cm, DG = 7 cm and a wide angle ∠D = 128° between them. How long is FG, to the nearest tenth?

   15.3
5. 5.

   Zee's triangle DFG has DF = 12 cm, DG = 5 cm and a wide angle ∠D = 140° between them. How long is FG, to the nearest tenth?

   16.2
6. 6.

   Ari's triangle DFG has DF = 8 cm, DG = 14 cm and a wide angle ∠D = 102° between them. How long is FG, to the nearest tenth?

   17.5
7. 7.

   Bo's triangle DFG has DF = 11 m, DG = 15 m and ∠D = 43° between them. Choose the Law of Sines or Cosines. How long is FG, to the nearest tenth?

   10.2
8. 8.

   Esme's triangle DFG has DF = 14 m between ∠D = 48° and ∠F = 70°. Choose the Law of Sines or Cosines. How long is FG, to the nearest tenth?

   11.8
9. 9.

   Jun's triangle DFG has DF = 9 m, DG = 17 m and ∠D = 61° between them. Choose the Law of Sines or Cosines. How long is FG, to the nearest tenth?

   14.9
10. 10.

    Kira's triangle DFG has DF = 25 m between ∠D = 36° and ∠F = 81°. Choose the Law of Sines or Cosines. How long is FG, to the nearest tenth?

    16.5