Law of Sines and Cosines Practice

• Side a is opposite angle α, and b is opposite β

• Side a is adjacent to angle α, and b is adjacent to β

• Side a is opposite angle β, and b is opposite α

Set up the law of sines to find side AB.

Find the angle at B.

• 35

• 209

• 87

• 29

The angle at B is 29^o.

Set up the law of sines to find side BC.

Which equation could NOT be used to find x?

(Choose the equation that is set up incorrectly.)

If a triangle has 1 angle and 2 sides, there are often two possible triangles. You solve law of sines to find the first possible angle for the triangle.

How do you find the second possible angle?

• Subtract your first answer from 180^o

• Subtract your first answer from 360^o

• Add your first answer to 180^o

• Subtract the angle on the triangle from your first answer

A triangle has side lengths 46 and 31. The angle opposite the side with length 46 measures 53 degrees.

Which equation can be used to find the angle opposite the side with length 31?