Copyright © 2013, 2009, 2005 Pearson Education, Inc. 1 6 Inverse Circular Functions and...

Preview:

Citation preview

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 1

6

Inverse Circular Functions and Trigonometric Equations

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 1

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 2

6.1 Inverse Circular Functions

6.2 Trigonometric Equations I

6.3 Trigonometric Equations II

Inverse Circular Functions and Trigonometric Equations6

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 3

Inverse Circular Functions6.1Inverse Functions ▪ Inverse Sine Function ▪ Inverse Cosine Function ▪ Inverse Tangent Function ▪ Remaining Inverse Circular Functions ▪ Inverse Function Values

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 4

Find y in each equation.

6.1 Example 1 Finding Inverse Sine Values (page 249)

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 5

6.1 Example 1 Finding Inverse Sine Values (cont.)

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 6

6.1 Example 1 Finding Inverse Sine Values (cont.)

is not in the domain of the inverse sine function, [–1, 1], so does not exist.

A graphing calculator will give an error message for this input.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 7

Find y in each equation.

6.1 Example 2 Finding Inverse Cosine Values (page 250)

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 8

Find y in each equation.

6.1 Example 2 Finding Inverse Cosine Values (cont)

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 9

6.1 Example 3 Finding Inverse Function Values (Degree-Measured Angles) (page 253)

Find the degree measure of θ in each of the following.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 10

6.1 Example 4 Finding Inverse Function Values With a Calculator (page 254)

(a) Find y in radians if

With the calculator in radian mode, enter as

y = 1.823476582

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 11

6.1 Example 4(b) Finding Inverse Function Values With a Calculator (page 254)

(b) Find θ in degrees if θ = arccot(–0.2528).

A calculator gives the inverse cotangent value of a negative number as a quadrant IV angle.

The restriction on the range of arccotangent implies that the angle must be in quadrant II, so, with the calculator in degree mode, enter arccot(–0.2528) as

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 12

6.1 Example 4(b) Finding Inverse Function Values With a Calculator (cont.)

θ = 104.1871349°

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 13

6.1 Example 5 Finding Function Values Using Definitions of the Trigonometric Functions (page 254)

Evaluate each expression without a calculator.

Since arcsin is defined only in quadrants I and IV, and

is positive, θ is in quadrant I.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 14

6.1 Example 5(a) Finding Function Values Using Definitions of the Trigonometric Functions (cont.)

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 15

6.1 Example 5(b) Finding Function Values Using Definitions of the Trigonometric Functions (page 266)

Since arccot is defined only in quadrants I and II, and

is negative, θ is in quadrant

II.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 16

6.1 Example 5(b) Finding Function Values Using Definitions of the Trigonometric Functions (cont.)

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 17

6.1 Example 6(a) Finding Function Values Using Identities

(page 255) Evaluate the expression without a calculator.

Use the cosine difference identity:

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 18

6.1 Example 6(a) Finding Function Values Using Identities

(cont.) Sketch both A and B in quadrant I. Use the Pythagorean theorem to find the missing side.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 19

6.1 Example 6(a) Finding Function Values Using Identities

(cont.)

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 20

6.1 Example 6(b) Finding Function Values Using Identities

(page 255) Evaluate the expression without a calculator.

Use the double-angle sine identity:

sin(2 arccot (–5))

Let A = arccot (–5), so cot A = –5.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 21

6.1 Example 6(b) Finding Function Values Using Identities

(cont.) Sketch A in quadrant II. Use the Pythagorean theorem to find the missing side.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 22

6.1 Example 6(b) Finding Function Values Using Identities

(cont.)

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 23

6.1 Example 7(a) Finding Function Values in Terms of u

(page 256) Write , as an algebraic expression in u.

Sketch θ in quadrant I. Use the Pythagorean theorem to find the missing side.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 24

6.1 Example 7(a) Finding Function Values in Terms of u

(cont.)

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 25

6.1 Example 7(b) Finding Function Values in Terms of u

(page 256) Write , u > 0, as an algebraic expression in u.

Sketch θ in quadrant I. Use the Pythagorean theorem to find the missing side.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 26

6.1 Example 7(b) Finding Function Values in Terms of u

(cont.)

Use the double-angle sine identity to find sin 2θ.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 27

Trigonometric Equations I6.2Solving by Linear Methods ▪ Solving by Factoring ▪ Solving by Quadratic Methods ▪ Solving by Using Trigonometric Identities

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 286-28

6.2 Example 1a Solving a Trigonometric Equation by Linear Methods (page 262)

is positive in quadrants I and III.

The reference angle is 30° because

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 29

6.2 Example 1 Solving a Trigonometric Equation by Linear Methods (cont.)

Solution set: {30°, 210°}

b) for all solutions

Solution set: {30° + 180°n, where n is any integer}

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 30

6.2 Example 2 Solving a Trigonometric Equation by Factoring (page 263)

or

Solution set: {90°, 135°, 270°, 315°}

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 31

6.2 Example 3 Solving a Trigonometric Equation by Factoring (page 263)

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 32

6.2 Example 3 Solving a Trigonometric Equation by Factoring (cont.)

has one solution,

has

two solutions, the angles in

quadrants III and IV with the

reference angle .729728:

3.8713 and 5.5535.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 33

Trigonometric Equations II6.3Equations with Half-Angles ▪ Equations with Multiple Angles

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 34

6.3 Example 1 Solving an Equation Using a Half-Angle Identity (page 269)

(a) over the interval and (b) give all solutions.

is not in the requested domain.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 35

6.3 Example 1 Solving an Equation Using a Half-Angle Identity (cont.)

This is a cosine curve with period

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 36

6.3 Example 2 Solving an Equation With a Double Angle

(page 270)

Factor.

or

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 37

6.3 Example 3 Solving an Equation Using a Multiple Angle Identity (page 270)

From the given interval 0° ≤ θ < 360°, the interval for 2θ is 0° ≤ 2θ < 720°.

Copyright © 2013, 2009, 2005 Pearson Education, Inc. 38

6.3 Example 3 Solving an Equation Using a Multiple Angle Identity (cont.)

Since cosine is negative in quadrants II and III, solutions over this interval are

Recommended