8.3 Ratios in Right Triangles

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8.3 Ratios in Right Triangles

• To find trig ratios using right triangles
• To solve problems using trig ratios

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Background
trigonometry- the word comes from 2 Greek words
trigon-meaning triangle metron meaning measure.
A ratio of the lengths of sides of a right
triangle .
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SOH CAH TOA
AN
OS
pposi te
pposi te
djacent
ypotenuse
IN
ypotenuse
djacent
What to remember
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Example
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
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A
C
12
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Example
Find the value of each ratio to the nearest
ten-thousandth
sin 7o
.1219
cos 30o
.8660
Example
Find the measure of each angle to the nearest
tenth degree
tan C 9.4618
sin A .7245
A sin-1 .7245
C 84o
A 46.4o
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Example
Find x
determine the relationship between the given
angle and the sides
x
63o
cross multiply
solve for x
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.891x 20
x 22.45
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Homework

• Put this in your agenda
• Pg 416 17 - 37 odd, 38 - 49