Introduction to the Law of Cosines

Given a triangle with b = 2, c = 5, and m∠A = 58°, what is the length of a?  Round to the nearest tenth.

• 4.9
• 6.3
• 4.3
• 3.7

Given a triangle with b = 3, c = 9, and m ∠A = 118°, what is the length of a?  Round the answer to the nearest tenth.

• 10.1
• 10.7
• 8.0
• 7.0

Find the missing side.

• 15.9 in.

• 22.8 in.

• 19.2 in.

• 521.1 in.

In ΔABC, a = 3, b = 5, and c = 7.  What is m∠C?

• 22°
• 38°
• 60°
• 120°

Solve triangle: A=29°a=22 B=112°

• b=34.87 C=39° c=22.7
• b=45.9 C=54° c=56.3
• b=42.07 C=39° c=28.56

Solve triangle: a=25 b=13 c=17

• A=112.2° B= 28.8° C= 39.0°
• A= 124.2° B=14.9° C=40.9°
• A=137.1° B=9.8° C=33.1°

Find QR

• 34.7 km
• 2.2 km
• 13.74
• 31.1 km

Find angle T

• 62.2 degrees
• 53.1 degrees
• 59.5 degrees
• 64.7 degrees

Find XZ

• 16.004 meters
• 544.165 meters
• 34.7 meters
• 1204.165 meters

Which Law would you use?

• Law of Sines
• Law of Cosines
• Law of the Jungle
• Law of Gravity