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Subsection 2.3 The Unit Circle and Trigonometric Functions Exercises

  1. For each triangle below, find all missing sides and angles.
    1. A right triangle labeled A, B, and C. The right angle is at point C, indicated by a square. The base of the triangle extends horizontally from C to B and is labeled 6 meters. The hypotenuse connects A to B. The vertical side connects A to C. The angle at A, between the vertical side and the hypotenuse, is labeled pi over three.
      Figure 2.3.14.
    2. A right triangle labeled A, B, and C. The right angle is at point C, indicated by a square. The hypotenuse runs from point B to point A and is labeled 12 meters. A vertical segment connects A to C. The angle at A, between the vertical segment and the hypotenuse, is labeled 72 degrees. The base of the triangle extends horizontally from B to C.
      Figure 2.3.15.
  2. Refer to the function \(Q(x)=\frac{(x-4)(x+1)}{(x+2)(x+6)}\text{.}\)
    1. What is the domain of \(Q\text{?}\)
    2. Graph \(Q(x)\) so that the important features are visible, and label them.
    3. Describe the interval(s) on which \(Q\) is increasing.
    4. Find the average rate of change of \(Q\) on the interval \(-1 \leq x \leq 1\text{.}\)
    5. Find the average rate of change of \(Q\) on the interval \(1 \leq x \leq 10\text{.}\)
    6. Find an interval on which the average rate of change of \(P\) is 0.
  3. \(x\) \(a(x)\)
    \(-1\) 3
    0 6
    1 9
    2 12
    Table 2.3.16. Table of values for \(a(x)\)
    \(x\) \(b(x)\)
    -1 3
    0 6
    1 12
    2 24
    Table 2.3.17. Table of values for \(b(x)\)
    1. Decide which type of function (linear, quadratic, exponential) best fits the data for \(a(x)\text{.}\) Explain your reasoning.
    2. Write a function equation for \(a(x)\text{.}\)
    3. Solve the equation \(a(x)=12\text{.}\)
    4. Using the function equation you wrote for \(a(x)\text{,}\) solve the inequality \(a(x) \geq 12\text{.}\)
    5. Using the function equation you wrote for \(a(x)\text{,}\) solve \(a(x)=48\text{.}\)
    6. Find the inverse function \(a^{-1}\text{.}\)
    7. Decide which type of function (linear, quadratic, exponential) best fits the data for \(b(x)\text{.}\) Explain your reasoning.
    8. Write a function equation for \(b(x)\text{.}\)
    9. Solve the equation \(b(x)=12\text{.}\)
    10. Using the function equation you wrote for \(a(x)\text{,}\) solve \(b(x) < 12\text{.}\)
    11. Using the function equation you wrote for \(b(x)\text{,}\) solve \(b(x)=48\text{.}\)
    12. Find the inverse function \(b^{-1}\text{.}\)
  4. Solve the following equations.
    1. \(\displaystyle 2^{x+1} \cdot 3^{x+2} = 23328\)
    2. \(\displaystyle \sqrt{x+1} \sqrt{x-39}=21\)
    3. \(\displaystyle \frac{1}{2}\ln (t+3) +\frac{1}{2} \ln (t-4) = \ln (12)\)
  5. Let \(a(x)=3^x\text{,}\) \(b(x)=3^{-x}\text{,}\) \(c(x)=\frac{1}{x^3}\text{.}\) Write a function equation for each function below, using the exponent rules to simplify the equation and write without negative exponents.
    1. \(\displaystyle f(x)=(c \circ b)(x)\)
    2. \(\displaystyle k(x)=c(x) \cdot a(x)\)
    3. \(\displaystyle g(x)=(c(x))^{-2}\)
    4. \(\displaystyle h(x)=2 (b(x))^2\)
    5. \(\displaystyle j(x)=a(x)\cdot b(x)\)
  6. Suppose that \(\sin \alpha = \frac{1}{2}\text{.}\) Use your work in the β€œImportant Angles" section to determine possible value(s) of \(\alpha\text{,}\) where \(0 \leq \alpha < 2\pi\text{.}\)
  7. Suppose that \(\cos \beta = \frac{\sqrt{2}}{2}\text{.}\) Use your work in the β€œImportant Angles" section to determine possible value(s) of \(\beta\text{,}\) where \(0 \leq \beta < 2\pi\text{.}\)
  8. A carousel has a diameter of 44 feet. The ride turns counterclockwise.
    1. Draw a diagram of the carousel in the \(xy\)-plane with the center at the origin.
    2. What is the distance traveled by a rider along the outer rim of the carousel as she travels through an angle of \(\frac{\pi}{3}\text{?}\) If the rider began at the point \((22,0)\text{,}\) what are the rider’s coordinates after traveling through an angle of \(\frac{\pi}{3}\text{?}\)
  9. A Ferris wheel has a diameter of 30 feet, and is mounted so that the bottom of the wheel is 4 feet off the ground. The ride turns counterclockwise as seen by the operator.
    1. Draw a diagram of the Ferris wheel in the \(xy\)-plane.
    2. Write an equation to describe the points on the Ferris wheel.
    3. Find the distance traveled by someone riding through one complete turn of the wheel.
    4. Find the distance traveled by someone ridlng from the 7 o’clock position to the 11 o’clock position.
    5. The wheel makes 1 turn every 25 seconds. A rider boards the wheel and travels a distance of 50 feet. How long did this take?
    6. What are the coordinates of a rider when she is in the 11 o’clock position on the wheel?
    7. What is the height above ground of a rider when her position is at an angle of \(\frac{\pi}{4}\) with the horizontal?
  10. Solve each equation.
    1. \(\displaystyle \frac{5}{n^2}-\frac{2n-4}{5n}=\frac{n-6}{n^2}\)
    2. \(\displaystyle 3r+3-\frac{5}{r}=\frac{1}{r}\)
    3. \(\displaystyle \frac{n-4}{n}=\frac{n+5}{n^2-4n}=\frac{2n^2-9n-5}{n^2-4n}\)
  11. Let \(m(x)=\sqrt[5]{x}\text{,}\) \(n(x)=x^2\text{,}\) and \(p(x)=\frac{1}{x^4}\text{.}\)
    1. Write \(m(n(x))\) as a function of \(x\) with a single exponent.
    2. Write \(m(n(x)p(x))\) as a function of \(x\) with a single exponent.
    3. Solve \(n(p(x))=128\)
    4. Solve \(m(x) \leq 1024\)
  12. The graph of \(f(x)\) is shown below. Let \(g(x)=f(2(x+1))-3\text{.}\)
    A graph on an x–y coordinate plane showing a piecewise function. For negative x-values, the graph begins near the x-axis and curves upward to the point (0, 4). From x equals 0 to x equals 3, the graph is a horizontal line at y equals 4. From x equals 3 to x equals 5, the graph decreases linearly from (3, 4) to (5, 0). The x-axis and y-axis are shown with tick marks and labels at 0 and 5.
    Figure 2.3.18.
    1. Describe the transformations that would be required to transform \(f(x)\) in to \(g(x)\text{.}\)
    2. On the same set of axes, sketch the graph of \(g(x)\text{.}\)
    3. What are the domain and range of \(f(x)\text{.}\)
    4. What are the domain and range of \(g(x)\text{.}\)