The Law of Cosines

Use Law of Cosines to find angle T

• 62.2°

• 53.1°

• 59.5°

• 64.7°

Which of the following formulas shows the Law of Cosines?

• c² = a² + b² - 4ac + cosA

• c² = a² - b² - 2abcosC

• c² = a² + b² - 2abcosC

• (cos A)/a = (cos B)/b

Find QR

• 34.7 km

• 2.2 km

• 13.74

• 31.1 km

Find BC

• A

• B

• C

• D

Which Law would you use? (a)  

• Law of Sines

• Law of Cosines

​ (a)   ​​ 4. Which law should I use for the given triangle?

• Law of Sines AFTER testing for #of Triangles

• Law of Sines then switch to Law of Cosines

• Law of Sines only

• None, use Right Triangle Trig

• Law of Cosines only

• Law of Cosines then switch to Law of Sines

Which law should I use for the given triangle?

• Law of Sines AFTER testing for #of Triangles

• Law of Sines then switch to Law of Cosines

• Law of Sines only

• None, use Right Triangle Trig

• Law of Cosines only

• Law of Cosines then switch to Law of Sines

Find angle Z

• 20.15°

• 71.23°

• 51.06°

• 57.71°

Find m<C

• A

• B

• C

• D

8.Solve for x

• 3.85

• 4.25

• 3.35

• 5.65