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Assessment for Unit 3: Trigonometric and Polar Functions
Select the one best answer for each question.
1. The depth of water at the end of a pier varies with the tides throughout the day. On a specific day, the high tide of 14 feet occurs at 2:00 a.m. The following low tide of 4 feet occurs at 8:00 a.m. The depth of the water can be modeled by a sinusoidal function $d(t)$, where $t$ is the time in hours since midnight. Which of the following best describes the amplitude and period of $d(t)$?
2. A pendulum swings back and forth, and its horizontal displacement $x(t)$ from the center position is modeled by a periodic function, where $t$ is time in seconds. At $t=0$, the pendulum is at its farthest point to the right (positive displacement). It first reaches the center position at $t=0.5$ seconds and continues to its farthest point to the left. Which of the following correctly identifies the period of the function and the behavior of the graph of $x(t)$ on the interval $(0, 1)$?
3. The function $h(t) = 10 + 4\sin\left(\frac{\pi}{4}t\right)$ models the height of a liquid in a container, in inches, at time $t$ seconds, where $0 \le t \le 8$. For which interval of $t$ is the height of the liquid strictly less than 8 inches?
4. Which of the following represents all solutions to the equation $2\cos(3x) + \sqrt{2} = 0$ ?
5. Which of the following expressions represents all real solutions for $x$ in the equation $4\sin(x) + 3 = 0$ ?
6. [Skill: 2.B | Topic: 3.11] The function $f$ is given by $f(\theta) = \csc(2\theta)$. Which of the following describes the values of $\theta$ for which the graph of $f$ has vertical asymptotes?
7. [Skill: 3.A | Topic: 3.11] Let $g$ be the function defined by $g(x) = 3 \sec x - 2$. Which of the following is the range of $g$?
8. [Skill: 3.B | Topic: 3.11] The function $h$ is defined by $h(x) = \sec x$. On which of the following intervals is the graph of $h$ both negative and increasing?
9. The function $f$ is defined by $f(\theta) = \frac{\sec^2 \theta - 1}{\sin^2 \theta}$ for all values of $\theta$ where the expression is defined. Which of the following is an equivalent expression for $f(\theta)$?
10. Which of the following expressions is equivalent to $\sin(3x)\cos(x) - \cos(3x)\sin(x)$ ?
11. What are all values of $\theta$ in the interval $0 \le \theta < 2\pi$ that satisfy the equation $2\cos^2 \theta + \sin \theta = 1$?
12. A point in the rectangular coordinate system is given by $(-2, -2\sqrt{3})$. Which of the following represents the polar coordinates $(r, \theta)$ of this point?
13. Which of the following gives the rectangular coordinates of the point with polar coordinates $(-6, \frac{5\pi}{4})$?
14. A complex number $z$ is defined by $z = 8(\cos \frac{7\pi}{4} + i \sin \frac{7\pi}{4})$. Which of the following represents $z$ in the form $a + bi$?
15. The polar function $r = f(\theta)$ is defined on the interval $0 \le \theta \le \pi$. Given that $f(\theta) < 0$ for all $\theta$ in the interval $\frac{\pi}{2} < \theta < \pi$, in which quadrant of the Cartesian plane will the graph of $r = f(\theta)$ appear corresponding to this interval?
Refer to the figure below.
16. The graph of the polar function $r = 1 + 2\cos(\theta)$ is shown in the polar coordinate system. The graph contains a larger outer loop and a smaller inner loop that passes through the pole. Which of the following intervals for $\theta$ corresponds to the portion of the graph that forms the inner loop?
17. A polar function is given by $r = f(\theta)$. On the interval $\frac{\pi}{2} < \theta < \pi$, the function $f$ is negative and increasing. Which of the following best describes the motion of a point on the graph of $r = f(\theta)$ as $\theta$ increases from $\frac{\pi}{2}$ to $\pi$?
18. Let $r = f(\theta)$ be a polar function where $f(\theta) < 0$ for all $\theta$ in the interval $\frac{\pi}{2} < \theta < \pi$. If the rate of change of $r$ with respect to $\theta$ is positive on this interval, which of the following statements is true about the distance between the point on the curve and the origin?
19. A polar function is defined by $r = 4 - 2\sin(\theta)$. What is the average rate of change of $r$ with respect to $\theta$ on the interval $0 \le \theta \le \frac{\pi}{2}$?
20. The graph of the polar function $r = f(\theta)$ is analyzed on the interval $\pi < \theta < 2\pi$. It is known that $f(\theta) < 0$ on this interval. If $f'(\theta)$ changes from negative to positive at $\theta = \frac{3\pi}{2}$, which of the following describes the point on the graph at $\theta = \frac{3\pi}{2}$?
21. An angle $\theta$ is in standard position in the $xy$-plane. The terminal ray of the angle intersects the unit circle at point $P$. If the measure of angle $\theta$ is $\frac{2\pi}{3}$ radians, what are the coordinates of point $P$?
22. The terminal ray of an angle $\theta$ in standard position intersects the unit circle at the point $P\left( -\frac{5}{13}, -\frac{12}{13} \right)$. What is the value of $\tan \theta$?
23. For an angle $\theta$ in standard position, the terminal ray intersects the unit circle at a point $(x, y)$. If $\tan \theta = -2$ and $x > 0$, what is the value of $\sin \theta$?
24. The terminal ray of an angle $\theta$ in standard position intersects a circle centered at the origin at the point $P(-8, 15)$. What is the value of $\cos \theta$?
25. An angle $\theta$ is in standard position, and its terminal ray intersects a circle of radius $6$ centered at the origin at point $Q$. If $\theta = \frac{5\pi}{6}$, what are the coordinates of point $Q$?
26. Circle $A$ and Circle $B$ are both centered at the origin. The radius of Circle $B$ is $k$ times the radius of Circle $A$, where $k > 1$. The terminal ray of an angle $\theta$ in standard position intersects Circle $A$ at point $(x_A, y_A)$ and Circle $B$ at point $(x_B, y_B)$. Which of the following correctly expresses $y_B$ in terms of $y_A$?
27. A point $P$ moves counterclockwise along the unit circle defined by $x^2 + y^2 = 1$, starting at the point $(1, 0)$. The angle of rotation, in radians, is given by $\theta$. Which of the following functions $f(\theta)$ represents the horizontal displacement of point $P$ from the $y$-axis?
28. Consider the function $g(\theta) = \sin \theta$, which represents the vertical displacement of a point on the unit circle. On which of the following intervals is the graph of $g(\theta)$ both negative and decreasing?
29. The function $f$ is given by $f(\theta) = -4 \cos\left(3\theta - \frac{\pi}{2}\right) + 1$. What are the amplitude and period of $f$?
30. A sinusoidal function $g$ has a minimum value of $-5$ and a maximum value of $9$. Which of the following gives the values of the amplitude and the midline of the graph of $g$?
31. The vertical position of a point on a vibrating string is modeled by the function $p(t) = \sin(8\pi t)$, where $t$ is measured in seconds. What is the frequency of the vibration in cycles per second?
32. [Skill: 2.B | Topic: 3.6] A sinusoidal function is given by the equation $f(\theta) = -4 \sin\left(\frac{\theta}{3}\right) + 2$. Which of the following correctly identifies the amplitude and period of the function?
33. [Skill: 1.C | Topic: 3.6] The graph of the function $h$ is the result of transforming the graph of $f(x) = \sin(x)$. The transformations applied to $f$ are a vertical dilation by a factor of 5, a horizontal compression by a factor of $\frac{1}{2}$, and a horizontal translation of $\frac{\pi}{4}$ units to the right. Which of the following defines $h(x)$?
34. [Skill: 1.B | Topic: 3.7] A scientist records the vertical position y , in centimeters, of a mass suspended from a spring at various times t , in seconds. The data is shown in the table below. | t | 0 | 2 | 4 | 6 | 8 | |:---:|:---:|:---:|:---:|:---:|:---:| | y | 12 | 18 | 12 | 6 | 12 | Which of the following functions best models the data?
35. [Skill: 2.B | Topic: 3.7] The number of hours of daylight in a certain city varies sinusoidally over the course of a year. The maximum number of daylight hours is 14.5, occurring at t = 172 days. The minimum number of daylight hours is 9.5, occurring at t = 355 days. Which of the following functions d(t) could model the number of daylight hours t days after the start of the year?
36. [Skill: 2.B | Topic: 3.7] A Ferris wheel with a diameter of 50 feet rotates at a constant speed, completing one full revolution every 3 minutes. A rider boards the wheel at its lowest point, which is 5 feet above the ground, at time t = 0 minutes. Which of the following functions models the rider's height h(t) , in feet, above the ground?
Refer to the figure below.
37. The figure below displays a unit circle in the xy-plane. A ray extending from the origin forms an angle θ in standard position and intersects the unit circle at point P with coordinates (x, y). Which of the following expressions represents the slope of the terminal ray and is equivalent to tan(θ)?
38. The function f is defined by f(θ) = tan(θ). Which of the following statements correctly describes the domain of f and the behavior of its graph at the excluded values?
39. The function g is given by g(x) = 3tan(2x - π). What are the period of g and the equations of the vertical asymptotes of the graph of g?
40. The function $f$ is defined by $f(x) = \arcsin(x)$. Which of the following tables correctly describes the domain and range of $f$?
41. What is the value of $\arccos\left(-\frac{\sqrt{2}}{2}\right)$ ?
42. Which of the following is equivalent to $\arctan\left(\tan\left(\frac{4\pi}{3}\right)\right)$ ?
43. [Skill: 2.B | Topic: 3.4] A point $P$ moves counterclockwise along the unit circle in the $xy$-plane. The coordinates of $P$ are given by $(x, y) = (\cos \theta, \sin \theta)$, where $\theta$ is the angle in standard position measured in radians. As the angle $\theta$ increases from $\frac{\pi}{2}$ to $\pi$, which of the following statements correctly describes the behavior of the sine and cosine functions?
44. [Skill: 2A | Topic: 3.1] The water level in a harbor changes periodically due to the tides. At 2:00 AM ($t = 2$ hours), the water level reaches its maximum height of 15 meters. At 8:00 AM ($t = 8$ hours), the water level reaches its minimum height of 7 meters. If the water level $H(t)$ is modeled as a periodic function of time $t$ in hours, which of the following statements is true?
45. [Skill: 2B | Topic: 3.6] A sinusoidal function $f(\theta)$ has the following key points over one cycle: - It crosses its midline at $\left(\frac{\pi}{4}, 1\right)$ and is increasing there. - It reaches a maximum at $\left(\frac{\pi}{2}, 4\right)$. - It crosses its midline again at $\left(\frac{3\pi}{4}, 1\right)$. - It reaches a minimum at $(\pi, -2)$. - It crosses its midline again at $\left(\frac{5\pi}{4}, 1\right)$. Which of the following could be an equation for $f(\theta)$?
Answer all parts of each question. Answers must be in essay form. Outlines or lists alone are not acceptable.
Question 46:
Question 47:
Question 48:
Question 49: