Trigonometry 1 (Right-angled Triangles)

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Trigonometry
Trigonometry is concerned with the relationship
between the angles and sides of triangles. An
understanding of these relationships enables
unknown angles and sides to be calculated without
recourse to direct measurement. Applications
include finding heights/distances of objects.
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30o
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35o
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40o
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45o
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324 m
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• Eiffel Tower Facts
• Designed by Gustave Eiffel.
• Completed in 1889 to celebrate the centenary of
  the French Revolution.
• Intended to have been dismantled after the 1900
  Paris Expo.
• Took 26 months to build.
• The structure is very light and only weighs 7 300
  tonnes.
• 18 000 pieces, 2½ million rivets.
• 1665 steps.
• Some tricky equations had to be solved for its
  design.

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Make up a Mnemonic!
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The Trigonometric Ratios (Finding an unknown
angle).
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The Trigonometric Ratios (Finding an unknown
angle).
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SOH CAH TOA
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SOH CAH TOA
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Explain why the angles of elevation and
depression are always equal.
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SOH CAH TOA
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A 25 m tall lighthouse sits on a cliff top, 30 m
above sea level. A fishing boat is seen 100m from
the base of the cliff, (vertically below the
lighthouse). Find the angle of depression from
the top of the lighthouse to the boat.
SOH CAH TOA
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A 22 m tall lighthouse sits on a cliff top, 35 m
above sea level. The angle of depression of a
fishing boat is measured from the top of the
lighthouse as 30o. How far is the fishing boat
from the base of the cliff?
SOH CAH TOA