Geometry 8-2 Trigonometric Ratios

1
Geometry 8-2 Trigonometric Ratios

• A trigonometric (trig) ratio is a ratio of two
  sides of a right triangle.
• Use trig ratios when the right triangle only has
  one side length given and it is not a special
  right triangle (30-60 or 45-45)

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1st Trigonometric Ratio

• The sine (sin)

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2nd Trigonometric Ratio

• The cosine (cos)

4
3rd Trigonometric Ratio

• The tangent (tan)

5
Recall the 30-60-90 Special Right Triangle

• Find the sin of the 60 angle.

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Recall the 45-45-90 Special Right Triangle

• Find the tan of the 45 angle.

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Word Problem

• You and your friends decide to build a bike ramp
  using a 4 ft piece of wood. You make a 20 angle
  with the ground. How high above the ground will
  the back wheel be when your bike goes off the
  ramp?

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Another Example

• Find the length of side BC.

10.2 ft
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Example

• Find the length of RT.

R
12
350 m
T
S