Trigonometric RatiosMath 2Y

Trigonometric ratios

Trig ratio- ratio of the lengths of two sides of a right Δ

Always round to four decimal places

3 basic trig ratios

Sine (sin) sin

Cosine (cos) cos

Tangent (tan) tan

hyp

opp

hyp

adj

adj

opp

Just remember Chief…

SOHCAHTOAin

is

pp

over

ypot

os

is

dj

over

ypot

an

is

pp

over

dj

Ratios of s A and BA B

c

aAsin

c

bAcos

b

aAtan

c

bB sin

c

aB cos

a

bB tan

A

BC a

b

c

Ex: Find sin, cos, & tan of A & B.Asin A= 12/13 = .9231cos A= 5/13 = .3846tan A= 12/5 = 2.4

Bsin B= 5/13 = .3846cos B= 12/13 = .9231tan B= 5/12 = .4167

C

A

B

13

12

5

Ex. Find sin A and sin 30o.

30°

60°1

2

A

BC

sin A = ½ or .5

sin 30 = .5

√3

Ex. Find sin B and sin 45o.

45°

45°

A

BC1

1

7071.2

2or

2

1 sin B

sin 45o = .7071

√2

Assignment

Use your textbook…

pg. 159 #1-3pg. 168 #1-6

(Be sure to read the directions for each section!)