+ All Categories
Home > Documents > Mathematics 5 SN TRIGONOMETRY PROBLEMS...

Mathematics 5 SN TRIGONOMETRY PROBLEMS...

Date post: 04-Apr-2020
Category:
Upload: others
View: 15 times
Download: 0 times
Share this document with a friend
31
Mathematics 5 SN TRIGONOMETRY PROBLEMS 2 If x , 4 3 , 3 2 , which one of the following statements is TRUE? A) sin x > 0 and cos x > 0 C) sin x < 0 and cos x > 0 B) sin x > 0 and cos x < 0 D) sin x < 0 and cos x < 0 If , 2 < t < 2 3 , which one of the following statements is TRUE? A) cos t > 0 and sin t > 0 C) cos t < 0 and sin t > 0 B) tan t > 0 and cos t < 0 D) sin t < 0 and tan t < 0 Given the functions f(x) = tan x and g(x) = sin x. What are the values for which the functions f and g are 0 in [0, ]? A) 0, 2 C) 2 , 0 B) 0, D) 0, 2 , 1 2 3
Transcript

Mathematics 5 SN

TRIGONOMETRY PROBLEMS 2

If x ,4

3 ,

3

2

, which one of the following statements is TRUE?

A)

sin x > 0 and cos x > 0

C)

sin x < 0 and cos x > 0

B)

sin x > 0 and cos x < 0

D)

sin x < 0 and cos x < 0

If ,2 < t < 2

3

, which one of the following statements is TRUE?

A)

cos t > 0 and sin t > 0

C)

cos t < 0 and sin t > 0

B)

tan t > 0 and cos t < 0

D)

sin t < 0 and tan t < 0

Given the functions f(x) = tan x and g(x) = sin x.

What are the values for which the functions f and g are 0 in [0, ]?

A)

0, 2

C)

2

, 0

B)

0,

D)

0, 2

,

1

2

3

What is the solution set of sin x 1 = 0 in ?

A)

{1}

C)

{x | x =

2 + n, n Z}

B)

2

D)

{x | x =

2 + 2n, n Z}

4

What is the solution set of the equation 2sin2x 4cos2x + 1 = 0 where x

2,

2

-?

A)

6 ,

6

-

C)

4

B)

3 ,

3

-

D)

4 ,

4

-

If x [0, 2π[, find the solution set of the following equations :

a) sin2x + cos x = 1

b) 2sin2x cos x 2 = 0

Show your work.

a)

Work

Result : The solution set is _______________.

5

6

b)

Work

Result : The solution set is _______________.

What are the zeros in the following equation if x [0, 2]?

2sin2x 1 = 0

A)

4

- ,

4

C)

4

7 ,

4

B)

4

3 ,

4

D)

4

7 ,

4

5 ,

4

3 ,

4

Which values of x belonging to

2

3,0 satisfy the equation 4 sin3x sin x = 0?

The values of x belonging to

2

3,0 and that satisfy the equation are

_______________________________________________.

7

8

2

3Sin x in the circle with centre O, show on the

right.

Furthermore, AB // OP and m OA = 1 unit.

What is the area of the shaded region?

Show all your work.

Show all your work.

Answer: The area of the shaded region is __________ square units.

x E

A

P

B

F O

x E

A

P

B

F O

9

Find all the solutions of the equation 2cos2x 3sin x 3 = 0 such that

x

2 ,

2

3 . Give your solution in radian measure.

Show all your work.

Show all your work.

2cos2x 3sin x 3 = 0 , x

2 ,

2

3 .

Answer:

The values of x in the domain are __________________ radians.

10

What are the exact values of A that satisfy the following trigonometric equation?

sin A cot A + 2 cos2 A = 1, A [0, 2]

Show all your work.

sin A cot A + 2 cos2 A = 1, A [0, 2]

Answer:

The solution is A = __________________.

11

Given the following trigonometric equation:

2 sin2 x + 5 sin x 3 = 0, x [0, 2]

What are the exact values of x that satisfy this equation?

The exact values of x are __________ and __________.

12

Strange geometric formations, known as crop circles, have appeared in fields around the world. The creators of

the crop circle shown below would like to surround their design with a border, in the shape of an equilateral

triangle.

The circles that were used to make the design are congruent to the circle whose equation is:

x2 + y2 6x 2y 26 = 0

The circles are externally tangent to one another and tangent to the border.

What is the length of the border?

Round your answer to the nearest hundredth of a unit.

Show all your work.

13

Show all your work.

Answer:

To the nearest hundredth of a unit, the border measures __________.

Given the trigonometric equation:

2 cos2x + cos x = 1, x [, ]

What are the exact values of x that satisfy this equation?

The exact values of x satisfying the given equation are:

_________________________________________________.

14

A hyperbola and a trigonometric function are drawn on the same Cartesian plane. The equation of the

hyperbola is 114425

22

yx

.

F1 F2

y

x

The foci of the hyperbola are directly below two of the maxima of the trigonometric function.

Which of the following is an equation of the trigonometric function?

(Where necessary, the numbers have been rounded.)

A)

13

13cos8.28 xy

C)

11

11cos3.23 xy

B)

13

13

2cos8.28 xy

D)

11

11

2cos3.23 xy

15

Consider the equation 2 cos2 3 sin = 3

What are the solutions, in radian measure, to the equation for which 0 2?

Show all your work.

Show all your work. 0 2

2 cos2 3 sin = 3

Answer

In radian measure, the exact answers are ______________________.

16

Given the following trigonometric equation:

2 sin2x + 3 = 9 cos x, x [0, 2]

What exact values of x satisfy this equation?

The solution(s) to this equation is (are) __________________________.

Given 2 cos2 x + 3 sin x 3 = 0, x

2,0 .

What are the exact values of x?

Show all your work.

2 cos2 x + 3 sin x 3 = 0, x

2,0 .

Answer:

The exact values of x are _______________________________.

17

18

Prove the following trigonometric identity.

xx

xx cos1

cos1

sinsin

Prove the following trigonometric identity.

Show all your work.

xx

xx cos1

cos1

sinsin

19

Solve the following trigonometric equation. Give the exact value(s).

2 sin2 x 3 cos x = 3 x π0,

Show all your work.

2 sin2 x 3 cos x = 3 x π0,

Answer:

The exact value(s) is (are) ___________________________ .

20

Find all solutions of 6 sin2 x 5 sin x + 1 = 0 in the interval 0, 2.

Express any inexact solutions to the nearest hundredth.

Show all your work.

6 sin2 x 5 sin x + 1 = 0

Solutions:

_______________________________________________________

21

2- Correction key

B

D

B

D

D

1

2

3

4

5

a) Work : (example)

sin2x + cos x = 1

1 cos2x + cos x = 1

cos2x cos x = 0

cos x (cos x 1) = 0

cos x = 0 or cos x = 1

2

x or

2

3 or x = 0

Result : The solution set is .2

3 ,

2 0,

b) Work : (example)

2sin2x cos x 2 = 0

2(1 cos2x) cos x 2 = 0

2 2cos2x cos x 2 = 0

2cos2x + cos x = 0

cos x (2cos x + 1) = 0

cos x = 0 or cos x = 2

1-

6

2

x or

2

3 or

3

2x or

3

4

Result : The solution set is

2

3,

3

4,

3

2,

2

D

The values of x belonging to

2

3,0 and that satisfy the equation are

,

6

5,

6,0 and

6

7.

7

8

Example of an appropriate solution

Measure of angle x

sin x = 2

3

m x = sin1

2

3

m x = 60 or m x = 3

radians

Base AB of triangle AOB

32

32ABm

Height FO of triangle AOB

2

160cosFOm

Area of triangle AOB

43.04

32

2

13Area

square units

Area of sector AOB

Area of sector AOB = (1)2

360

120 1.05 square units

Area of the shaded region 1.05 0.43 = 0.62 square units

x E

A

P

B

F O

9

Answer: The area of the shaded region is 0.62 square units.

Example of an appropriate solution

2cos2x 3sin x 3 = 0

2(1 sin2x) 3sin x 3 = 0

2 2sin2x 3sin x 3 = 0

-2sin2x 3sin x 1 = 0

2sin2x + 3sin x + 1 = 0

(2sin x + 1)(sin x + 1) = 0

2sin x + 1 = 0 sin x + 1 = 0

2sin x = -1 sin x = -1

sin x = 2

1-

x = 6

7,

6

11 x =

2

3

Answer The values of x in the domain are 6

11 and

2

3.

10

Example of an appropriate method

sin A cot A + 2 cos2 A = 1

sin A Asin

Acos + 2 cos2 A = 1

cos A + 2 cos2 A = 1

2 cos2 A + cos A 1 = 0

(2 cos A 1)(cos A + 1) = 0

cos A = 2

1 or cos A = -1

A = 3

or

3

5 or A =

Answer 3

, ,

3

5

The exact values of x are 6

and

6

5.

11

12

Example of an appropriate method

Equation of the circle in standard form

x2 + 6x + y2 2y = 26

(x 3)2 + (y 1)2 = 26 + 9 + 1

(x 3)2 + (y 1)2 = 36

Each radius measures 6 units

Since the three circles are congruent, the border forms an equilateral triangle.

According to the diagram on the right, A B C D

Note: Adjustments will have to be made

for different labelling.

COD is a right triangle, m OC = 6 units and m CDO = 30°

13

tan30° = CDm

OCm =

CDm

6

m CD = 10.39

m AD = m AB + m BC + m CD

= 10.39 + 12 + 10.39

32.78

Perimeter: P = 3 32.78

= 98.34

Answer: To the nearest hundredth of a unit, the border measures 98.34.

Note: Do not penalize students who did not round the answer.

Students who determined the radius of the circle have shown a partial understanding of the

problem.

The exact values of x are -, 3

,3

- ,

A

14

15

Example of an appropriate solution

01θsin1θsin2

01θsin3θsin2

3θsin3θsin22

3θsin3θsin12

3θsin3θcos2

2

2

2

2

1-θsinor2

1-θsin

For 2

1-θsin For 1-θsin

Reference angles: 6

θ

2

The sine function is negative in Quadrants III and IV.

Answer: In radian measure, the exact answers are

6

11,

2

3,

6

The exact values of x are 3

and

3

5.

16

17

Example of an appropriate solution

01sin3sin2

01sin3sin2-

03sin3sin22

03sin3sin12

03sin3cos2

2

2

2

2

2

xx

xx

xx

xx

xx

01sin1sin2 xx

2

1sin

01sin2

x

x

sin x 1 = 0

sin x = 1

Answer: The exact values of x are 6

x or

2

x .

18

Example of an appropriate proof

x

xx

xx

xx

x

xx

x

xx

xx

cos1

cos1cos1

cos1cos1

cos1cos1

cos1

cos1cos1

sin

cos1cos1

sinsin

2

2

Deduct marks if student is unable to complete the proof, but is able to arrive at x

x

cos1

cos1 2

Example of an appropriate solution

xx

xx

xx

xx

xx

xx

xx

or3

2

1cosor2

1cos

1cos1cos20

1cos3cos20

3cos3cos22

3cos3cos12

3cos3sin2

2

2

2

2

Answer: The exact values are πor3

2π xx .

19

20

Students who were able to arrive at 0 = (2 cos x + 1) (cos x + 1) have shown they have a partial understanding of the problem.

Example of an appropriate solution

80.2,6

5,

6,34.0

6

5

680.234.0

2

1sin

3

1sin

01sin201sin3

01sin21sin3

01sin5sin6 2

x

xx

xx

xx

xx

xx

oror

Note: Students who used an appropriate method to determine two of the four answers have shown they

have a partial understanding of the problem.

21


Recommended