Yr 2 w-up

x

1.

32o

16 cmxo

4 ft

5 ft

42o20 cm

2.

For 1-5 solve – you decide what to use, set up ratio, round to the hundredths place

xo17 m

22 m15 m

4.

5.33 cm

20o

x

41 cm

3.

xo

17 yd

22 yd10.64 cm 32.360

37.690

42.890

15.07 cm

Problem Solving with Trigonometry

Lesson 12.5

Do the following when solving trigonometry word problems…

1. Draw a picture.2. Decide which trigonometry formula you must

use.3. Solve the word problem.

SOH – CAH – TOA LAW OF SINES

LAW OF COSINES SAS TRIANGLE AREA

cCsin

bBsin

aAsin

Ccosab2bac 222 Csinab21

A

Right Triangle Ratios

A large helium balloon is tethered to the ground by two taut lines. One line is 100 feet long and makes an 80° angle with the ground. The second line makes a 40° angle with the ground. How long is the second line, to the nearest foot? How far apart are the tethers?

80° 40°

100 ft x

x80sin

10040sin

80sin10040sinx

40sin80sin100

x

x = 153 ft

60°y = 135 ft

y60sin

10040sin

60sin10040siny

40sin60sin100

y

y

A ship’s sonar locates a treasure chest at a 12° angle of depression. A diver is lowered 40 meters to the ocean floor. How far (to the nearest meters) does the diver need to swim along the ocean floor to get the treasure chest?

12°

12°40 m

x

x40

12tan

4012tanx

12tan40

x

x = 188 m

Farmer Joe needs to fence his triangular plot of land for his cows. The angle between two sides measures 83°. One side is 122 ft and the other is 215 ft. How much fencing does farmer Joe need to the nearest foot? What is the area of his plot of land?

83°

122

ft

215 ft

x

83cos2151222215122x 222

73.715,54x 2 234x

234 ft

215122234 571 ft

83sin)215)(122(21

Area

Area = 13017 ft2

HOMEWORK:12.5 Worksheet and p. 648 1, 3, 4, 6, 8