4-1 Right Triangle Trigonometry

Transcription

1 Find the exact values of the six trigonometric functions of θ. 1. sin θ =, cos θ =, tan θ =, csc θ 5. sin θ =, cos θ =, tan θ =, csc θ =, sec θ =, cot θ = =, sec θ =, cot θ = 2. sin θ =, cos θ =, tan θ =, csc 6. sin θ =, cos θ =, tan θ =, csc θ =, sec θ =, cot θ = θ =, sec θ =, cot θ = 3. sin θ =, cos θ =, tan θ =, csc θ 7. sin θ =, cos θ =, tan θ =, csc θ =, sec θ =, cot θ = =, sec θ =, cot θ = 4. sin θ =, cos θ =, tan θ =, csc θ =, sec θ =, cot θ = 8. sin θ =, cos θ =, tan θ =, csc θ =, sec θ =, cot θ = 4 esolutions Manual - Powered by Cognero Page 1

2 Use the given trigonometric function value of the acute angle θ to find the exact values of the five remaining trigonometric function values of θ. 9. sin θ = cos θ =, tan θ =, csc θ =, sec θ =, cot θ = 13. cos θ = sin θ =, tan θ =, csc θ =, sec θ =, cot θ = 14. tan θ = 10. cos θ = sin θ =, tan θ =, csc θ =, sec θ =, cot θ = 11. tan θ = 3 sin θ =, cos θ =, csc θ =, sec θ =, cot θ = 12. sec θ = 8 sin θ =, cos θ =, tan θ = 3, csc θ =, cot θ = sin θ =, cos θ =, csc θ =, sec θ =, cot θ = cot θ = 5 sin θ =, cos θ =, tan θ =, csc θ =, sec θ = 16. csc θ = 6 sin θ =, cos θ =, tan θ =, sec θ =, cot θ = 17. sec θ = sin θ =, cos θ =, tan θ =, csc θ =, cot θ = esolutions Manual - Powered by Cognero Page 2

3 18. sin θ = cos θ =, tan θ =, csc θ =, sec θ =, cot θ = Find the value of x. Round to the nearest tenth, if necessary MOUNTAIN CLIMBING A team of climbers must determine the width of a ravine in order to set up equipment to cross it. If the climbers walk 25 feet along the ravine from their crossing point, and sight the crossing point on the far side of the ravine to be at a 35º angle, how wide is the ravine? 17.5 ft 28. SNOWBOARDING Brad built a snowboarding ramp with a height of 3.5 feet and an 18º incline. Draw a diagram to represent the situation. b. Determine the length of the ramp. b ft esolutions Manual - Powered by Cognero Page 3

4 29. DETOUR Traffic is detoured from Elwood Ave., left 0.8 mile on Maple St., and then right on Oak St., which intersects Elwood Ave. at a 32 angle. Draw a diagram to represent the situation. b. Determine the length of Elwood Ave. that is detoured º º b. 1.3 mi 30. PARACHUTING A paratrooper encounters stronger winds than anticipated while parachuting from 1350 feet, causing him to drift at an 8º angle. How far from the drop zone will the paratrooper land? º 59º 190 ft Find the measure of angle θ. Round to the nearest degree, if necessary º º º esolutions Manual - Powered by Cognero Page 4

5 38. 69º 39. PARASAILING Kayla decided to try parasailing. She was strapped into a parachute towed by a boat. An 800-foot line connected her parachute to the boat, which was at a 32º angle of depression below her. How high above the water was Kayla? 41. ROLLER COASTER On a roller coaster, 375 feet of track ascend at a 55º angle of elevation to the top before the first and highest drop. Draw a diagram to represent the situation. b. Determine the height of the roller coaster. b. 307 ft 424 ft 40. OBSERVATION WHEEL The London Eye is a 135-meter-tall observation wheel. If a passenger at the top of the wheel sights the London Aquarium at a 58º angle of depression, what is the distance between the aquarium and the London Eye? 42. SKI LIFT A company is installing a new ski lift on a 225-meter-high mountain that will ascend at a 48º angle of elevation. Draw a diagram to represent the situation. b. Determine the length of cable the lift requires to extend from the base to the peak of the mountain. 84 m b. 303 m esolutions Manual - Powered by Cognero Page 5

6 43. BASKETBALL Both Derek and Sam are 5 feet 10 inches tall. Derek looks at a 10-foot basketball goal with an angle of elevation of 29, and Sam looks at the goal with an angle of elevation of 43. If Sam is directly in front of Derek, how far apart are the boys standing? 46. MOUNT RUSHMORE The faces of the presidents at Mount Rushmore are 60 feet tall. A visitor sees the top of George Washington s head at a 48º angle of elevation and his chin at a 44.76º angle of elevation. Find the height of Mount Rushmore. about 3.1 ft 44. PARIS A tourist on the first observation level of the Eiffel Tower sights the Musée D Orsay at a 1.4º angle of depression. A tourist on the third observation level, located 219 meters directly above the first, sights the Musée D Orsay at a 6.8º angle of depression. Draw a diagram to represent the situation. b. Determine the distance between the Eiffel Tower and the Musée D Orsay. 47. about 500 ft Solve each triangle. Round side lengths to the nearest tenth and angle measures to the nearest degree. B = 70º, b 16.5, c 17.5 b m 45. LIGHTHOUSE Two ships are spotted from the top of a 156-foot lighthouse. The first ship is at a 27º angle of depression, and the second ship is directly behind the first at a 7º angle of depression. Draw a diagram to represent the situation. b. Determine the distance between the two ships. 48. X = 29º, y 37.1, z P 43º, Q 47º, r 34.0 b. 964 ft esolutions Manual - Powered by Cognero Page 6

7 50. D 77º, E 13º, d BASEBALL Michael s seat at a game is 65 feet behind home plate. His line of vision is 10 feet above the field. Draw a diagram to represent the situation. b. What is the angle of depression to home plate? 51. K 19º, j 18.0, k W 14, Y 76, y 3.9 b. 56. HIKING Jessica is standing 2 miles from the center of the base of Pikes Peak and looking at the summit of the mountain, which is 1.4 miles from the base. Draw a diagram to represent the situation. b. With what angle of elevation is Jessica looking at the summit of the mountain? 53. f 19.6, h 17.1 b. Find the exact value of each expression without using a calculator. 57. sin R 30º, S 60º, t cot sec 30 esolutions Manual - Powered by Cognero Page 7

8 60. cos tan csc sec θ = Without using a calculator, determine the value of x. 2 Without using a calculator, find the measure of the acute angle θ in a right triangle that satisfies each equation. 63. tan θ = cos θ = cot θ = SCUBA DIVING A scuba diver located 20 feet below the surface of the water spots a shipwreck at a 70º angle of depression. After descending to a point 45 feet above the ocean floor, the diver sees the shipwreck at a 57º angle of depression. Draw a diagram to represent the situation, and determine the depth of the shipwreck sin θ = csc θ = 2 30 about 100 ft esolutions Manual - Powered by Cognero Page 8

9 Find the value of cos θ if θ is the measure of the smallest angle in each type of right triangle tan 45 sec 30 < 81. ENGINEERING Determine the depth of the shaft at the large end d of the air duct shown below if the taper of the duct is 3.5º about SOLAR POWER Find the total area of the solar panel shown below. about 17.9 in ft 2 Without using a calculator, insert the appropriate symbol >, <, or = to complete each equation. 75. sin 45 cot 60 > 76. tan 60 cot 30 = 77. cos 30 csc 45 < 78. cos 30 sin 60 = 79. sec 45 csc 60 > esolutions Manual - Powered by Cognero Page 9

10 82. MULTIPLE REPRESENTATIONS In this problem, you will investigate trigonometric functions of acute angles and their relationship to points on the coordinate plane. GRAPHICAL Let P(x, y) be a point in the first quadrant. Graph the line through point P and the origin. Form a right triangle by connecting the points P, (x, 0), and the origin. Label the lengths of the legs of the triangle in terms of x or y. Label the length of the hypotenuse as r and the angle the line makes with the x-axis θ. b. ANALYTICAL Express the value of r in terms of x and y. c. ANALYTICAL Express sin θ, cos θ, and tan θ in terms of x, y, and/or r. d. VERBAL Under what condition can the coordinates of point P be expressed as (cos θ, sin θ)? e. ANALYTICAL Which trigonometric ratio involving θ corresponds to the slope of the line? f. ANALYTICAL Find an expression for the slope of the line perpendicular to the line in part a in terms of θ. 83. PROOF Prove that if θ is an acute angle of a right triangle, then. and Sample answer: For an acute angle θ of a right triangle, sin θ =, cos θ =, tan θ =, and cot θ =. Using these definitions, = = = tan θ. Similarly, = = = cot θ. 84. ERROR ANALYSIS Jason and Nadina know the value of sin θ = a and are asked to find csc θ. Jason says that this is not possible, but Nadina disagrees. Is either of them correct? Explain your reasoning. Nadina; sample answer: The cosecant function is the reciprocal function of the sine function. Therefore, if sin θ = a, then csc θ =, where a Writing in Math Explain why the six trigonometric functions are transcendental functions. b. r = c. sin θ =, cos θ =, tan θ = d. Sample answer: when r = 1 e. tan θ f. cot θ The trigonometric functions are transcendental functions because they cannot be expressed in terms of algebraic operations. For example, there is no way to find the value of θ in y = cos θ by adding, subtracting, multiplying, or dividing a constant and θ or raising θ to a rational power. esolutions Manual - Powered by Cognero Page 10

11 86. CHALLENGE Write an expression in terms of θ for the area of the scalene triangle shown. Explain. 89. cos A < cos B False; sample answer: In ABC, the m B < m A, cos B , and cos A Therefore, cos B > cos A, and thus the statement is false. A = ; Sample answer: If you draw the height of the triangle, it forms two right triangles. The length of the height is equal to a sin θ using the formula A = bh, where the base of the triangle is 90. tan A < tan B b and the height is a sin θ. 87. PROOF Prove that if θ is an acute angle of a right triangle, then (sin θ) 2 + (cos θ) 2 = 1. Sample answer: Given a triangle with hypotenuse c and legs a and b, let sin θ = and cos θ =. By the Pythagorean Theorem, c 2 = a 2 + b 2. true 91. Writing in Math Notice on a graphing calculator that there is no key for finding the secant, cosecant, or cotangent of an angle measure. Explain why you think this might be so. Sample answer: Since the cosine function is the reciprocal of the secant function, the sine function is the reciprocal of the cosecant function, and the tangent function is the reciprocal of the cotangent function, you can find the value of a secant, cosecant, or cotangent function on a graphing calculator by finding one divided by the reciprocal of the function. Therefore, (sin θ) 2 + (cos θ) 2 = 1. REASONING If A and B are the acute angles of a right triangle and m A < m B, determine whether each statement is true or false. If false, give a counterexample. 88. sin A < sin B true esolutions Manual - Powered by Cognero Page 11

12 92. ECONOMICS The Consumer Price Index (CPI) measures inflation. It is based on the average prices of goods and services in the United States, with the annual average for the years set at an index of 100. The table shown gives some annual average CPI values from 1955 to Find an exponential model relating this data (year, CPI) by linearizing the dat Let x = 0 represent Then use your model to predict the CPI for Sketch and analyze the graph of each function. Describe its domain, range, intercepts, asymptotes, end behavior, and where the function is increasing or decreasing. 95. f (x) = 3 x 2 D = (, ), R = (, 0); no x-intercept, y- intercept: ; horizontal asymptote at y = 0; Sample answer: y = e x ; about Solve each equation. Round to the nearest hundredth. 93. e 5x = , ) 96. f (x) = 2 3x decreasing on ( 94. 2e x 7 6 = D = (, ), R = (1, ); no x-intercept, y- intercept: ; horizontal asymptote at y = 1; increasing on (, ) esolutions Manual - Powered by Cognero Page 12

13 97. f (x) = 4 x NEWSPAPERS The circulation in thousands of papers of a national newspaper is shown. Let x equal the number of years after Create a scatter plot of the dat b. Determine a power function to model the dat c. Use the function to predict the circulation of the newspaper in D = (, ), R = (, 0); no x-intercept, y- intercept: 4096; horizontal asymptote at y = 0; increasing on (, ) Solve each equation , 8 b. y = x c. 611, SAT/ACT In the figure below, what is the value of z? , 1 A 15 B 15 C 15 D 30 E 30 B esolutions Manual - Powered by Cognero Page 13

14 103. REVIEW Joseph uses a ladder to reach a window 10 feet above the ground. If the ladder is 3 feet away from the wall, how long should the ladder be? F 9.39 ft G ft H ft J ft G 104. A person holds one end of a rope that runs through a pulley and has a weight attached to the other end. Assume that the weight is at the same height as the person s hand. What is the distance from the person's hand to the weight? A 7.8 ft B 10.5 ft C 12.9 ft D 14.3 ft A 105. REVIEW A kite is being flown at a 45 angle. The string of the kite is 120 feet long. How high is the kite above the point at which the string is held? F 60 ft G 60 ft H 60 ft J 120 ft G esolutions Manual - Powered by Cognero Page 14