Download Trig Ratio NOTES

NOTES: TRIG RATIOS
Recall from geometry: “SOH CAH TOA”
Date: ___________
A
O
H
Sin  =
O – Opposite
H – Hypotenuse
A - Adjacent
B
Cos  =
A
H
Tan =
O
A
C
Note: To solve a triangle means to find all unknown sides and angles.
You can use your calculator to find the sin, cos or tan of any angle.
Example 1:
Evaluate. Make sure your calculator is in DEGREE mode. Round to three decimal places
a) sin 53˚
b) cos 86˚
c) tan 71˚
You can also use your calculator to find the value of an angle, given its sin, cos or tangent value. To
do this, we use the “inverse function” on the calculator!
Example 2:
Find the measure of each angle.
a) sin A = 0.7183
b) cos C = 0.9781
Example 3:
Find the lengths of the missing sides (x) in the
given triangles.
c) tan X = 1.1788
Example 4:
Find the measure of the missing angles (  ).
a)
a)
37o
12 cm
x

5 cm
10 cm
b)
b)

x
9 cm
53
o
17 cm
15 cm
You try!
Find the length of the missing side (x)
b) Find the measure of
the missing angle (  )

a)
37o
x
4 cm
10 cm
Find the length of the missing side (x)
11 cm
b) Find the measure of
the missing angle (  )
a)
29o
2 cm
x

10 cm
6 cm