Pre-Calculus Notes

Law of Sines

In any triangle ABC, A

c b

B a C

Sin A° = Sin B° = Sin C°

a b c

1. From a point in a suburban school, students can see the top of a skyscraper in the city if they look 41° west of north. Traveling 4.1 miles due west from the school, the same skyscraper is seen in the direction 26° west of north. How far is the school from the skyscraper? Draw a picture and solve.

2). In DXYZ, XY = 12, YZ = 10, and m ÐX = 38°. Find m Ð Z. Draw a picture and solve.

3). In DABC, m Ð C = 40° , m Ð 30°, and c = 15. Find the two other sides. Draw a picture and solve.