Section 7.6Law of Sines

Law of Sines• How can I solve triangles with the Law of Sines?

• How can I solve problems with the Law of Sines?

Terms• Solving a triangle: Find all three sides and all

three angles

• Naming a triangle: Angles are paired up with the opposite side

A

a

B

b

C

c

Law of Sines

A

a

B

b

C

c

Law of Sines• Used when you do not have a right triangle

• Remember the sum of angles in a triangle is 180°

A

a

B

b

C

c

Example• Find p in ∆PQR when mP = 17o, mR = 29 o, and r =

8.

Example• Find mL to the nearest degree in ∆ LMN if n = 7, l

= 9, and mN = 43 o.

Example• Find c in ∆ ABC when mA = 47o, mC = 23 o, and a

= 16.•  

Example• Solve ∆ DEF if m D = 112, mF = 8, and f = 2.

Application• A 5-foot fishing pole is anchored to the edge of a

dock. If the distance from the foot of the pole to the point where the fishing line meets the water is 45 feet, about how much fishing line that is cast out is above the surface of the water?

Application• A 46-foot telephone pole tilted at an angle of 7o

from the vertical casts a shadow on the ground. Find the length of the shadow to the nearest foot when the angle of elevation to the sun is 33 o.

Classwork• In groups of two, create your own Law of Sines

problem. It must have enough information to be solved, a picture and the solution worked out. Make sure both your names are on it.

Homework• Section 7.6• Page 381• 16 – 29• 32, 33, 38, 39

• Study Guide and Review• Page 393• 8, 12, 13, 16, 18, 21, 26, 29

Lesson Plan• Intro• Dealing with triangles that are not right

• Standards-• Supplies – slides, whiteboard, Timing - 1 day• Essential Questions- slide 2• Input – slides 3-5• Guided Practice – slides 6-12• Independent Practice – Bookwork