# trigonometry

2,132 results, page 10

1. ### circle trigonometry

sin θ=2/3 and θ correspond to a point in quadrant 2. cos θ=
2. ### Calculus

So,y(t) = 2.5e^-t cos2t I need to find the derivative, which is y'(t)= -2.5e^-t(2sin 2t +cost 2t) . And now I need to find t when y'(t) = 0 (I know 2.5 e^-t is never zero.) I need to use trigonometry identity to find it ?
3. ### trigonometry

Suppose θ is an angle in standard position whose terminal side lies in Q II. If sin θ = 13 12 , find sec θ.
4. ### help with trigonometry??

Jacob is standing 112 m from a building. The angle of elevation when he looks up to the top of the building is 62°. How tall is the building? I don't really understand how to solve this, please help!!
5. ### Trigonometry

determine real numbers a and b so that the expression 8sin^2(theta) + 2cos^2(theta) can be rewritten as (a)sin^2(theta) + b? If you can help me out on how to start it would be great.
6. ### Trigonometry

What is cos (pi/2 - x) secx using the fundamental identities to simplify the expression. I think I have the right answer but I want to check to make sure. Well, cos (pi/2 - x) is something you should've seen already. It's just another name for sin(x). Also, sec(x) is the same ...
7. ### Math/Trigonometry

Find the exact value of cosθ if sinθ=-2/3, and θis in standard position with its terminal side in Quadrant IV.
8. ### trigonometry

How to solve a vertical pole 8 feet tall cast a shadow 5 feet long on level ground.find the angle which the rays of the sun makes with the horizontal.
9. ### Summer School Calculus

Add the following vectors , 7m/s [N30E] and 2m/s [S17E], using trigonometry. Once you draw these out into diagrams, you use the triangle law yes? How do you find the angles to use in the cosine and sine law? A little confused, thanks for the help.
10. ### Trigonometry

5. If a trig equation has one answer, how many answers will it have? (Provided you do not restrict the domain?) 6. Why are the graphs of the inverse functions restricted to one period of the function? I only need to answer these two to finish my homework and I can't figure out...
11. ### Trigonometry

Can you please help me verify these? >sin7x-sin5x= tanx(cos7x-cos5x) >(1-cosx)cot(1/2x) = sinx >1+tanx tan(x/2) = secx Its very confusing because of all the double-half angle formulas >_<
12. ### trigonometry(opt math)

From the roof and basement of a house 20m high,the angle of elevation of the top of a tower are 45 and 60 degres respectively. Find the height of the tower. (Ans=81.97m)
13. ### math

respected sir i want to know the table describing the values of angles of trigonometry functions. eg. sin,cos & tan 15,30,45,60,75,90 separately in table format. thanking you! padam singh.
14. ### trigonometry math

An aviator heads his airplane due west. He finds that because of a wind from the south, the course makes an angle of 20" with the heading. If his airspeed is 100 mi/h, what is his groundspeed and what is the speed of the wind?
15. ### Trigonometry

An observer in a lighthouse 350 feet above sea level observes two ships directly offshore. The angles of depression to the ships are 4° and 6.5°. How far apart are the ships?
16. ### trigonometry

A man 1.8 metre tall observes the angle of elevation of a tree to be 20 degrees, if he is standing 16 metres from the tree. Find the height of the tree.
17. ### Trigonometry

At a point on the ground 125 ft from the base of a tower, the angle of elevation to the top of the tower has a degree measure of 38 degrees. How high is the tower
18. ### Trigonometry

Solve for θ in the equation cos θ = -0.181 when 180º < θ < 360º. Round your answer to the nearest tenth of a degree.
19. ### Trigonometry

A passenger in an airplane flying at an altitude of 10 kilometers sees two towns directly to the left of the plane. The angles of depression to the towns are 28° and 55°. How far apart are the towns?
20. ### Math trigonometry identities

2sinθ cosaθ cotθ
21. ### Trigonometry

What are the phase shift and the vertical shift for the function f(x) = cos 4(x+5) + 3? And what direction is each shift going in (up or down)?
22. ### Trigonometry

Find the exact value of tan2(Beta) if sin(Beta) = 5/13 (Beta in Quadrant II)

24. ### Trigonometry

Solve the triangle in which sin A :sin B :Sin C =3:4:6and it's perimeter equals 52 cm
25. ### Trigonometry

find the exact value of sin 2α if cos α=4/5 (α in quadrant I)
26. ### Trigonometry

find the exact value of tan 2β if sin β=5/13 (β in quadrant II)
27. ### Trigonometry

If tan theta= 3 and Pi<theta<3Pi/2, find cos theta. Pi=3.141592654
28. ### Trigonometry

Find the exact value of tan2(Beta) if sin(Beta) = 5/13 (Beta in Quadrant II)
29. ### math (trigonometry)

A=170 degree then prove that Tan A/2=-1-rot(1+Tan^2 A)/Tan A
30. ### Trigonometry

If A + B + C = 180°, Prove that Sin² (A/2) + sin² (B/2) - sin²(C/2) = 1 – 2cos (A/2) cos (B/2) sin(C/2)
31. ### trigonometry

if sin where defined=1/5 and where defined is in quadrant I find the exact value of sin2 where defined
32. ### Trigonometry

An airplane approaches an airport. At a certain time, it is 939 m high. Its angle of elevation measured from the airport is 19.5◦. To the nearest metre, how far is the plane from the airport?
33. ### trigonometry

A motor cruising south along the highway is 16 km from the nearest town. After travelling a distance of 32 km, he finds that he is 19 km from the same town. Find the bearing of the town from the second position of the motorist.
34. ### Math

Hi I'm reviewing the following solution in my trigonometry text book and I can't figure out how they got their answer. If someone can help explain how they calculated 542.25 for a^2 (nothing I do comes up with that number): a2=b2+c2-2bcCosA a2=(16)^2+(11)^2 -2(16)(11)Cos118 a2...
35. ### Geometry

According to OSHA, a ladder that is placed against a wall should make a 75.5 degree angle with the ground for optimal safety. To the nearest tenth of a foot, what is the maximum height that a 10-ft ladder can safely reach?(trigonometry)
36. ### Trigonometry

Find the diameter of a pulley which is driven at 360 rpm by a belt moving at 40 ft/s. Then in 1 s the pulley turns through an angle theta measuring 12 pi radians and a point on the rim travels a distance s= 40 ft.
37. ### Trigonometry

Consider angle C such that sin C= 7/25 Sketch a diagram to represent angle C in standard position if cos C is negative Find the co-ordinates of a point P on the terminal arm of angle C.
38. ### Trigonometry

Find these quantities: i. Find all angles in the unit circle with secx=2.1754 . Give your answers in radians to 4 decimal places. ii. Find sec(arcsin(2x))
39. ### Trigonometry

a bicycle with 24inch diameter wheels is traveling at 15mi/hr. a) Find the angular speed of the wheels in rad/min. b)How many revolutions per minute do the wheels make?
40. ### Trigonometry

The angle of elevation to the top of a Building in New York is found to be 6 degrees from the ground at a distance of 1 mile from the base of the building. Using this information, find the height of the building.
41. ### trigonometry

The problem is: Solve each of the following equations over the interval [0,2Pi). 2sin^2 x - 1 = 0 The answers are: Pi/4, 3Pi/4, 5Pi/4, 7Pi/4 I know how to get the first two answers, but I'm not sure how you get the last two answers, since sin would be negative in quadrants 3 ...
42. ### Math (trigonometry)

MONDAY  December 3, 2012 SCHOOL SUBJECTS Art Business Computers English Foreign Languages Health Home Economics Math Music Physical Education Science Social Studies GRADE LEVELS Preschool Kindergarten Elementary School 1st Grade 2nd Grade 3rd Grade 4th Grade 5th Grade 6th ...
43. ### Trigonometry

Use a graph of the function to approximate the solution of the equation on the interval [−2π, 2π]. (List the solutions in increasing order from left to right on the x-axis. Round your answers to three decimal places.)
44. ### Trigonometry

Without using the Calculator, solve the ff: (show solution) a. Cos 18° b. Tan 18° c. Cot 18° d. Sin 9° e. Cos 9° [Hint: Using any of the formulas for Half- Angle, Double Angles, Reduction] Good Day!!! Thank you for the time. :)
45. ### Trigonometry

Use inverse trigonometric functions to find the solutions of the equation that are in the given interval, and approximate the solutions to four decimal places. (Enter your answers as a comma-separated list.) cos(x)(9cos(x) + 4) = 4; [0, 2π)
46. ### trigonometry

A sheet metal worker constructed a triangular metal flashing with sides of 6 ft., 5 ft., and 3 ft. If he charges \$2 per square foot for this type of work, then what should he charge? Do not use Heron’s formula. Justify and explain your reasoning.
47. ### Trigonometry

This is more of an opinion question: I'm working on Verifying Identities but I always have trouble knowing where to start. Once my teacher points it out i'm like "oh, duh" but on my own I have not the slightest idea on how to begin these; especially the tricky ones. Does ...
48. ### trigonometry

a question just like this one was on one of my homeworks..i asked for help but i didn't understand the explanation..so i had to gues..nd now i have that kind of quesion again on my homework. pleease explain this thoroughly find the value of s in the interval [0,pi/2] that ...
49. ### trigonometry

1.use a calculator to evaluate the expression cos31deg*cos149-sin31deg*sin149 A. -0.4695 B. -1 C. 0 D. -0.8829 i got B. is that correct? 2.Find the exact trigonometric function value. csc(-300deg) A. sqrt2 B. 2sqrt3/3 C. -sqrt3/3 D. -2 i don't know about this one..i can only ...
50. ### trigonometry

Write the function in terms of the cofnction with an acute angle. tan 18degrees A. sec18deg B. cot18deg C. cot72deg D. cot108deg find a solution for the equation. sin(2theta+20deg) = cos(3theta-5deg) thnkks:))

52. ### Trigonometry

Prove that sin(A-B)/cosAcosB + sin(B-C)/cosBcosC + sin(C-A)/cosCcosA = 0
53. ### Trigonometry

12. Find the exact value of sin(2x) if sin(x)=-1/2. sin(2x) = 2sin(x)cos(x)
54. ### trigonometry

given that θ=5/9 and pi/2<θ< pi, find the values of the other 5 trigonometric functions of θ
55. ### TRIGONOMETRY HELP

Prove that: cos²Θ - sin²Θ = 2cos²Θ - 1
56. ### Trigonometry

Find the exactly value of sin2(alpha) if cos(alpha) = 4/5 (alpha in Quadrant I)
57. ### Trigonometry

Let è be the angle between the x-axis and the line connecting the origin O(0,0) and the point P(−3,−4) , where 180<è<270. Given that sinè+cosè+tanè=−a/b, where a and b are coprime positive integers. What is the value of a+b?
58. ### Trigonometry

An observer on a cliff 1000 dm above sea level sights two ships due east. the angles of depression of the ships are 44o and 32o. Find the distance between the ships.
59. ### trigonometry

Peter has three sticks measuring 19 inches, 23 inches, and 27 inches. He lays form a triangle. Find the measure of the angle enclosed by the 19 inch and 23 insides to the nearest degree.
60. ### Trigonometry

You observe a plane approaching overhead and assume that its speed is 700 miles per hour. The angle of elevation of the plane is 16° at one time and 58° one minute later. Approximate the altitude of the plane
61. ### Math , trigonometry

From a point on the ground 20m from the base of a tree the angle of the elevation to the top of the tree is 47 degrees. Calculate the height the of the tree correct to the nearest metre ???
62. ### Trigonometry

if the lengths of the sides of an oblique triangle are 250 m. and the measure of the angle opposite of the later side is 37 degree 45'30", what are the possible lengths of the other sides?
63. ### Trigonometry

Let (7,-3) be a point on the terminal side of theta. Find the exact values of cos of theta, sec of theta and cot of theta?

65. ### Math-Trigonometry

The angles of elevation to the top of a mountain are measured from beacons A(22°) and B(40°) at sea. If the beacons are 125m apart, how high is the mountain?

Write each expression in the standard form for a complex number, a + bi. A. [3(cos(27°)) + isin(27°)]^5 B. [2(cos(40°)) + isin(40°)]^6 For A i got 2.67+1.36i and for B i got 1.53+1.29i
67. ### Trigonometry

Write each expression in the standard form for a complex number, a + bi. A. [3(cos(27°)) + isin(27°)]^5 B. [2(cos(40°)) + isin(40°)]^6 For A i got 2.67+1.36i and for B i got 1.53+1.29i
68. ### Plane trigonometry

A pulley having a diameter of 36 cm is turned by a belt that moves at the rate of 5m/sec . How many revolutions does the pulley make per/sec?
69. ### Trigonometry

A painter needs to cover a triangular region 62 meters by 68 meters by 70 meters. A can of paint covers 70 square meters. How many cans will be needed?
70. ### TRIGONOMETRY

3. The rectangular coordinates of a point are given. Find the polar coordinates of each point. b. (0,3) I figured out a, but I canNOT figure out b. Can someone please explain? :)I need to know how to do this for my final next week.
71. ### Trigonometry

Verify the identities algebraically. 1.) TAN^5 X= TAN³X SEC²X-TAN³X 2.) COS³X SIN²X= (SIN²X-SIN^4X)COS X

73. ### Trigonometry

Can you show steps on deriving the identity from the sum and difference formulas for cosine: sin a sin b = (1 / 2)[cos(a – b) – cos(a + b)]
74. ### Trigonometry

Help trig question involving discriminant? a)Find the value of the discriminant. b)Use any method to find the real roots of the equation if they exist. 2x^2+7x=0
75. ### trigonometry

Find the exact value of each expression(no calculator): 1) sin^2(30degrees) + 1/sec^2(20degrees) 2) sec(50degrees)*cos(50degrees)
76. ### Trigonometry

express in terms of sine and cosine. a) tan theta/ cot theta i know the answer is sin^2 theta / cos ^2 theta but how do you do it?
77. ### trigonometry

You are to run a conduit diagonally cross a parking lot that is 200 ft log and 60 ft wide. How much conduit will you need to complete this run?
78. ### Trigonometry

A sine function has an amplitude of 4/7, period of 2pi, horizontal shift of -3pi, and vertical shift of 1.  What is the y-value of the positive function at x= pi/2?
79. ### Trigonometry

Solve the equation on the interval 0 <= theta < 2pi for cot (theta) = 2. I know the answer is .46,3.61, but I don't know how to arrive at that answer on a ti-84 calculator.
80. ### algrbra/trigonometry

in triangle ABC, angle a=120, b=10, and c=18. What is the area of triangle ABC tot he nearest square inch?
81. ### Trigonometry

Since the radius of the wheel is 7 feet, point P goes 7 feet above and below the center of the wheel. From this information, you can find the amplitude. Write the value of this constant.
82. ### Trigonometry

A plane is 160 miles north and 85 miles east of an airport. If the pilot wants to fly directly to the airport, what bearing would be taken?
83. ### trigonometry

A plane flew 50 km on a bearing 63° 20', and then flew on a bearing of 153°20' for 120 km. Find the distance between the starting and ending point.
84. ### Trigonometry

Sarah used her calculator to find sin125 degree. She wrote down sin125 degrees = -.57. How could Sarah recognize that her answer is incorrect?
85. ### Trigonometry

Triangle PQR has vertices P(0, 1), Q(0, -4), and R(2, 5). Find the coordinates of R' to the nearest hundredth after rotating triangle PQR counterclockwise about the origin 45º.
86. ### Trigonometry

Triangle PQR has vertices P(0, 1), Q(0, -4), and R(2, 5). Find the coordinates of R' to the nearest hundredth after rotating triangle PQR counterclockwise about the origin 45º.
87. ### trigonometry

Express as a function : c.tan (810degrees + theta ) I'm confused between two answers . 1. that it would be tan 90 deg (which is undefined) 2. it would be cot theta ?? can you tell me what i should do to get the right answer.
88. ### Trigonometry

Two circles, whose radii are 12 inches and 16 inches respectively, intersect. The angle between the tangents at either of the points of intersection is 29'30'. Find the distance between the centers of the circles.
89. ### Trigonometry (Coterminal Angles)

What is the SMALLEST POSITIVE ANGLE that is coterminal with the angle having the radian measure of -10π/3? Is there any solution for this kind of question?
90. ### Trigonometry

AN AIRPLANE IS FLYING AT A HEIGHT OF 1000 m. THE ANGLE OF DEPRESSION OF AIRPORT A FROM THE PLANE IS 15°. CALCULATE THE HORIZONTAL DISTANCE BETWEEN THE AIRPLANE AND THE AIRPORT.
91. ### trigonometry

A 15-foot ladder is resting against a wall and makes an angle of 48 degree's with the ground. Find the height to which the ladder will reach on the wall
92. ### Trigonometry

ABC is a right triangle with AB = 2, BC = 3\sqrt{5}, AC = 7 and \angle ABC = 90^\circ. If \cos \angle BAC = \frac{a}{b}, where a and b are coprime positive integers, what is the value of a + b?
93. ### Trigonometry

A TREE STANDS ON HORIZONTAL GROUND. THE ANGLE OF ELEVATION OF THE TOP OF THE TREE FROM A POINT 50 m AWAY FROM THE BASE OF THE TREE IS 11.3°. CALCULATE THE HEIGHT OF THE TREE.
94. ### Trigonometry

A boat is 100 m from the bottom of a 75 m high cliff. Calculate the angle of elevation from the boat to the top of the cliff. (I've been trying to solve it but i have no idea how
95. ### Trigonometry

Triangle PQR has vertices P(0, 1), Q(0, -4), and R(2, 5). Find the coordinates of R' to the nearest hundredth after rotating triangle PQR counterclockwise about the origin 45º.
96. ### Trigonometry

What is the maximum integer value of x, where x<200, that satisfies the following inequalities: sin(90+180x/100)<0 and tan(180−180x/100)<0 ?
97. ### trigonometry

okay so in my review packet under the "calculator" section it says law of sines and law of cosines. i don't know what that means. i wikipedia-ed it but i don't understand what they are saying. Please help!
98. ### Trigonometry

Solve for the following equation to the nearest degree if needed for 0 less than equal to x less than equal to 360. sin^2x=cosx 2sin^2x+cosx-cos^2x=0
99. ### Trigonometry

Find tan theta if theta is an angle in standard position and the point with coordinates (â€“12, 5) lies on the terminal side of the angle.
100. ### Maths-Trigonometry

a kite is attached to a string that is 15m long. If the string makes an angle of 26 degrees to the horizontal the height of the kite is.