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JMerrill, 2010. WWe know that for a function to have an inverse function, it must be one-to-one (it must pass the Horizontal Line Test).

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Presentation on theme: "JMerrill, 2010. WWe know that for a function to have an inverse function, it must be one-to-one (it must pass the Horizontal Line Test)."— Presentation transcript:

1 JMerrill, 2010

2 WWe know that for a function to have an inverse function, it must be one-to-one (it must pass the Horizontal Line Test).

3 FFrom looking at a sine wave, it is obvious that it does not pass the Horizontal Line Test.

4  The Unit Circle in found in section 4.7.  We will use: ◦ Radians ◦ Exact answers (mostly) ◦ Quick board review of Unit Circle, quadrants on the wave, & converting to radian measure

5 IIn order to pass the Horizontal Line Test (so that sin x has an inverse that is a function), we must restrict the domain. WWe restrict it to

6 QQuadrant IV is QQuadrant I is AAnswers must be in one of those two quadrants or the answer doesn’t exist.

7 HHow do we draw inverse functions? SSwitch the x’s and y’s! Switching the x’s and y’s also means switching the axis!

8 DDomain/range of restricted sine wave? DDomain/range of inverse?

9 yy = arcsin x or y = sin -1 x BBoth mean the same thing. They mean that you’re looking for the angle where sin y = x.

10 FFind the exact value of: AArcsin ½ ◦T◦This means at what angle is the sin = ½ ? ◦π◦π/6 ◦(◦(5π/6 has the same answer, but falls in QIII, so it is not correct)

11  When looking for an inverse answer on the calculator, use the 2 nd key first, then hit sin, cos, or tan.  When looking for an angle always hit the 2 nd key first.  Last example: ◦ Degree mode, 2 nd, sin,.5 = 30. ◦ Radian mode: 2 nd, sin,.5 =.524 (which is pi/6)

12 FFind the value of: SSin -1 2 ◦T◦This means at what angle is the sin = 2 ? ◦W◦What does your calculator read? Why? ◦2◦2 falls outside the domain of an inverse sine wave

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14 DDomain and range of restricted wave? DDomain and range of the inverse?

15 WWe must restrict the domain NNow the inverse

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17 WWe must restrict the domain NNow the inverse

18 Graphing Utility: Graphs of Inverse Functions Graphing Utility: Graph the following inverse functions. a. y = arcsin x b. y = arccos x c. y = arctan x – ––  – 2 –– –3 3  –– Set calculator to radian mode.

19 Graphing Utility: Inverse Functions Graphing Utility: Approximate the value of each expression. a. cos – b. arcsin 0.19 c. arctan 1.32d. arcsin 2.5 Set calculator to radian mode.

20  Previously learned notation: ◦ f o g(x)g o f(x)

21 FFind tan(arctan(-5)) ◦-◦-5 (the tangent and its inverse cancel each other out!) FFind arcsin(sin ) ◦T◦The domain of the sine function is. Since is outside that domain, we’ll just say that the answer is: is outside the domain (unless you remember coterminal angles and can tell me the actual answer is FFind ◦O◦Outside the domain

22  Find the exact value of  Draw the graph using only the info inside the parentheses. (Easy way—completely ignore the fact that you have inverses!)

23 Example: x y 3 2 Positive so draw in Q1)

24  Find the


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