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Introduction to Trigonometry Part 2. Review: Adj / Opp / Hyp. Let b be your reference angle. A is the adjacent side (next to the angle). b. C. A. B is the opposite side (across from the angle). B. b. Next. C is always the hypotenuse. hyp. Longest. adj. opp. Across.
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Review: Adj/ Opp / Hyp • Let b be your reference angle • A is the adjacent side (next to the angle) b C A • B is the opposite side (across from the angle) B b Next • C is always the hypotenuse hyp Longest adj opp Across
But if we switch angles… • Now let a be your reference angle • A is the opposite (across from the angle) C A a • B is the adjacent (next to the angle) B Across • C is always the hypotenuse hyp Longest opp a adj Next
Trigonometry uses ratios of the sides • There are three sets of ratios for any triangle • sin…short for sine • cos…short for cosine • tan…short for tangent
So what are the formulas? Tan is Opposite over Adjacent Sin is Opposite over Hypotenuse Cos is Adjacent over Hypotenuse SOH CAH TOA
Another tangent example • Find side B. b C A = 6 25° B
An application • You look up at an angle of 65° at the top of a tree that is 10m away • the distance to the tree is the adjacent side • the height of the tree is the opposite side 65° 10m
Example 3 • Angle b = 66.4 ° • Side A = 4 cm • Find side C 66.4 ° C = x A = 4 a B
One last example… • Lucretia drops her walkman off the Leaning Tower of Pisa when she visits Italy • It falls to the ground 2 meters from the base of the tower • If the tower is at an angle of 88° to the ground, how far did it fall?
First draw a triangle • What parts do we have? • We have an angle • We have the Adjacent • We need the opposite • Since we are working with the adj and opp, we will use the tan formula B 88° 2m
So lets calculate • Lucretia’s walkman fell 57.27m B 88° 2m
What are the steps for doing one of these questions? • Label the sides • Choose SOH, CAH, or TOA • Solve the equation for the unknown value • Does the answer make sense?