Transcript 8.3 Ratios in Right Triangles

8.3 Ratios in Right Triangles
To find trig ratios using right
triangles
To solve problems using trig ratios
trigonometry- the word comes from 2 Greek words
trigon-meaning triangle
A ratio of the lengths of
sides of a right triangle .
A
Adjacent
metron meaning measure.
C
opposite
Sin 
hypotenuse
adjacent
Cos 
hypotenuse
opposite
opposite
Tan 
adjacent
B
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Find sin A, cos A, tan A, sin B, cos
B, and tan B. Express each ratio
as a fraction and as a decimal
B
13
5
C
12
A
12
5
5
cos
A


.
923
tan A 
.417
sin A 
 0.385
12
13
13
12
sin B 
.923
13
12
5
 2.4
cos B 
.385 tan B 
5
13
Find the value of each ratio to
the nearest ten-thousandth
sin 7o = .1219
cos 30o = .8660
Find the measure of each angle
to the nearest tenth degree
sin A = .7245
tan C = 9.4618
A = sin-1 .7245
A = 46.4o
C = 84o
Find x
determine the relationship between
the given angle and the sides
63o
x
cross multiply
solve for x
20
20
sin 63 
x
.891 20

1
x
.891x = 20
x = 22.45
Homework
• Put this in your agenda
• Pg 416 17 - 37 odd, 38 - 49