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iGCSE (2021 Edition)

7.09 Using radians

Worksheet
Radians
1

Calculate the following trigonometric ratios to two decimal places:

a

\sin \dfrac{35 \pi}{16}

b

\cos 6.87

c

\sin 7.26

d

\tan 7.26

e

\tan \left(\dfrac{- 3 \pi}{7}\right)

f

\cos \dfrac{2 \pi}{3}

g

\sin \left( - \dfrac{4 \pi}{3}\right)

h
\cos \dfrac{4 \pi}{5}
i
\sin \left( - \dfrac{4 \pi}{5} \right)
Exact values
2

Consider the following diagram:

a

Find the length of side h.

b

Hence, state the exact value of:

i
\sin \dfrac{\pi}{3}
ii
\sin \dfrac{\pi}{6}
iii
\tan \dfrac{\pi}{3}
iv
\cos \dfrac{\pi}{3}
v
\cot \dfrac{\pi}{6}
3

Consider the following diagram:

a

Find the length of the hypotenuse, h.

b

Hence, state the exact value of:

i
\sin \dfrac{\pi}{4}
ii
\cos \dfrac{\pi}{4}
iii
\tan \dfrac{\pi}{4}
iv
\cot \dfrac{\pi}{4}
v
\sec \dfrac{\pi}{4}
4

Consider the diagram of the unit circle:

Find the exact value of:

a
\sec \dfrac{\pi}{6}
b

\text{cosec } \dfrac{\pi}{4}

c

\cot \dfrac{\pi}{3}

5

Consider the unit circle diagram and state the exact value of the following trigonometric ratios:

a

\sin \dfrac{\pi}{2}

b

\cos \dfrac{3\pi}{2}

c

\tan \pi

d

\cos 0

e

\sec \dfrac{\pi}{2}

f

\sec \pi

g

\text{cosec } \dfrac{\pi}{2}

h

\sin \left(-2\pi\right)

-1
1
0
-1
1
\dfrac{\pi}{2}
6

Find the exact value of the following:

a

\sin \dfrac{\pi}{3} + \cos \dfrac{\pi}{3}

b

\sin \dfrac{\pi}{6} \cos \dfrac{\pi}{4}

c

\dfrac{\sin \dfrac{\pi}{3}}{\cos \dfrac{\pi}{6}}

d

\sin \dfrac{\pi}{4} \cos \dfrac{\pi}{6} + \tan \dfrac{\pi}{4}

e

\sin ^{2}\left(\dfrac{\pi}{6}\right) - \cos ^{2}\left(\dfrac{\pi}{3}\right)

f

2\sin ^{2}\left(\dfrac{\pi}{2}\right) + 3\cos ^{2}\left(\dfrac{\pi}{2}\right)

Exact values from reference angles
7

Consider the unit circle shown, where points A and B have the same \\ y-coordinates.

Suppose that \theta = \dfrac{10 \pi}{11}. State the size of the reference angle, \alpha.

8

Consider the unit circle shown, where the line through A and B passes through the origin, O.

Suppose that \theta = \dfrac{8 \pi}{7}. State the size of the reference angle, \alpha.

9

Consider the unit circle shown, where the points A and B have the same \\ x-coordinate.

Suppose that \theta = \dfrac{9 \pi}{5}. State the size of the reference angle, \alpha.

10

Find the exact value of the following:

a

\sin \dfrac{5 \pi}{6}

b

\tan \dfrac{3 \pi}{4}

c

\sin \dfrac{7 \pi}{6}

d

\cos \dfrac{7 \pi}{6}

e

\sin \dfrac{5 \pi}{3}

f

\cos \dfrac{5 \pi}{3}

g

\cos 4 \pi

h

\tan 9 \pi

i

\sin \dfrac{ 5\pi}{2}

j

\cos \dfrac{ 7\pi}{2}

k

\cos \dfrac{3 \pi}{4}

l
\sin \dfrac{5 \pi}{4}
m
\cos \dfrac{5 \pi}{4}
n
\tan \dfrac{5 \pi}{4}
o

\tan \dfrac{7 \pi}{6}

p

\tan \dfrac{11 \pi}{6}

11

Find the exact value of the following:

a

\sin \left( - \dfrac{17 \pi}{6} \right)

b

\cos \left( - \dfrac{17 \pi}{6} \right)

c

\cos \left( - \dfrac{4 \pi}{3} \right)

d

\tan \left( - \dfrac{17 \pi}{6} \right)

e

\text{cosec } \left( - \dfrac{17 \pi}{6} \right)

f

\sec \left( - \dfrac{17 \pi}{6} \right)

g

\cot \left( - \dfrac{17 \pi}{6} \right)

h

\cot 3 \pi

i
\text{cosec} \dfrac{5 \pi}{4}
j
\sec \dfrac{5 \pi}{4}
k
\cot \dfrac{5 \pi}{4}
12

Find the exact value of the following:

a

\dfrac{\left(\sin \dfrac{2 \pi}{3}\right) \left(\cos \dfrac{2 \pi}{3}\right) \left(\tan \dfrac{3 \pi}{4}\right)}{\tan \left( - \dfrac{\pi}{4} \right)}

b

\dfrac{\sin \dfrac{2 \pi}{3} + \cos \dfrac{5 \pi}{6} - \tan \dfrac{7 \pi}{4}}{\cos \dfrac{4 \pi}{3}}

Trigonometric functions
13

Consider the equation y = \sin x.

a

Complete the table with values in exact form:

x0\dfrac{\pi}{6}\dfrac{\pi}{2}\dfrac{5 \pi}{6}\pi\dfrac{7 \pi}{6}\dfrac{3 \pi}{2}\dfrac{11 \pi}{6}2 \pi
\sin x
b

Sketch a graph for y = \sin x on the domain -2\pi \leq 0 \leq 2\pi.

c

State the value of \sin \left(-2 \pi\right).

d

State the sign of \sin \left( \dfrac{- \pi}{12} \right).

e

State the sign of \sin \dfrac{13 \pi}{12}.

f

Which quadrant of a unit circle does an angle with measure \dfrac{13 \pi}{12} lie in?

14

Consider the equation y = \cos x.

a

Complete the table with values in exact form:

x0\dfrac{\pi}{3}\dfrac{\pi}{2}\dfrac{2 \pi}{3}\pi\dfrac{4 \pi}{3}\dfrac{3 \pi}{2}\dfrac{5 \pi}{3}2 \pi
\cos x
b

Sketch a graph for y = \cos x on the domain -2\pi \leq 0 \leq 2\pi.

c

State the value of \cos \pi.

d

State the sign of \cos \left( \dfrac{- \pi}{4} \right).

e

State the sign of \cos \dfrac{11 \pi}{6}.

f

Which quadrant of a unit circle does an angle with measure \dfrac{11 \pi}{6} lie in?

15

Consider the equation y = \tan x.

a

Complete the table with values in exact form:

x0\dfrac{\pi}{4}\dfrac{\pi}{2}\dfrac{3 \pi}{4}\pi\dfrac{5 \pi}{4}\dfrac{3 \pi}{2}\dfrac{7 \pi}{4}2 \pi
\tan x
b

Sketch the graph of y = \tan x on the domain -2\pi \leq 0 \leq 2\pi.

c

Graph the line y = 1 on the same coordinate plane.

d

Hence, state the exact solutions to the equation \tan x = 1 over this domain.

e

State the value of \tan \left(-2 \pi\right).

f

State the sign of \tan \left( \dfrac{- \pi}{6} \right).

g

State the sign of \tan \dfrac{9 \pi}{5}.

h

Which quadrant of a unit circle does an angle with measure \dfrac{9 \pi}{5} lie in?

16

Consider the graph of y = - \tan x and the plotted points A, B, C, D and E shown:

a

At which point is the graph of \\ y = -\tan x equal to zero?

b

At which point will the corresponding graph of y = -\cot x be undefined? Explain your answer.

\frac{1}{2}π
\frac{3}{2}π
x
-2
-1
1
2
y
17

Consider the identity \sec x = \dfrac{1}{\cos x} and the following table of values:

x0\dfrac{\pi}{4}\dfrac{\pi}{2}\dfrac{3 \pi}{4}\pi\dfrac{5 \pi}{4}\dfrac{3 \pi}{2}\dfrac{7 \pi}{4}2 \pi
\cos x1\dfrac{1}{\sqrt{2}}0- \dfrac{1}{\sqrt{2}}- 1- \dfrac{1}{\sqrt{2}}0\dfrac{1}{\sqrt{2}}1
\sec x
a

Complete the table for the function y=\sec x.

b

State the range for y=\sec x.

c

Sketch the graph of y = \sec x on the domain \left[-2\pi, 2 \pi\right].

18

Consider the identity \text{cosec } x = \dfrac{1}{\sin x} and the following table of values:

x0\dfrac{\pi}{4}\dfrac{\pi}{2}\dfrac{3 \pi}{4}\pi\dfrac{5 \pi}{4}\dfrac{3 \pi}{2}\dfrac{7 \pi}{4}2 \pi
\sin x0\dfrac{1}{\sqrt{2}}1\dfrac{1}{\sqrt{2}}0- \dfrac{1}{\sqrt{2}}- 1- \dfrac{1}{\sqrt{2}}0
\text{cosec } x
a

State the values of x in the interval \left[0, 2 \pi\right] for which \text{cosec } x is not defined.

b

Complete the table for the function y=\text{cosec } x.

c

State the range for y=\text{cosec } x.

d

Sketch the graph of y = \text{cosec } x on the interval \left[-2\pi, 2 \pi\right].

19

Consider the identity \cot x = \dfrac{\cos x}{\sin x} and the following table of values:

x0\dfrac{\pi}{4}\dfrac{\pi}{2}\dfrac{3 \pi}{4}\pi\dfrac{5 \pi}{4}\dfrac{3 \pi}{2}\dfrac{7 \pi}{4}2 \pi
\cos x1\dfrac{1}{\sqrt{2}}0- \dfrac{1}{\sqrt{2}}- 1- \dfrac{1}{\sqrt{2}}0\dfrac{1}{\sqrt{2}}1
\sin x0\dfrac{1}{\sqrt{2}}1\dfrac{1}{\sqrt{2}}0- \dfrac{1}{\sqrt{2}}- 1- \dfrac{1}{\sqrt{2}}0
\cot x
a

State the values of x in the interval \left[0, 2 \pi\right] for which \cot x is not defined.

b

Complete the table for the function y = \cot x.

c

State the x-intercepts of the graph of y = \cot x in the interval \left[0, 2 \pi\right].

d

Sketch the graph of y = \cot x on the interval \left[-2\pi, 2 \pi\right].

e

Describe the graph of y = \cot x.

20

Consider the identity \sec x = \dfrac{1}{\cos x}.

a

Complete the table for x-values close to x = \dfrac{\pi}{2} \approx 1.57, where x is given in radians. Round each value to two decimal places.

x11.51.561.571.581.62
\sec x
b

Describe happens to the value of \sec x as x approaches \dfrac{\pi}{2} from the left. Explain your answer.

21

Consider the identity \text{cosec } x = \dfrac{1}{\sin x}.

a

Complete the table for x-values close to x = \pi \approx 3.14, where x is given in radians. Round each value to two decimal places.

x33.13.133.143.153.24
\text{cosec } x
b

Describe what happens to the value of \text{cosec } x as x approaches \pi from the left. Explain your answer.

22

Consider the table of values for \text{cosec } x over the domain \left(0, 2 \pi\right):

x\dfrac{\pi}{4}\dfrac{\pi}{2}\dfrac{3 \pi}{4}\dfrac{5 \pi}{4}\dfrac{3 \pi}{2}\dfrac{7 \pi}{4}
\text{cosec } x\sqrt{2}1\sqrt{2}- \sqrt{2}- 1- \sqrt{2}
a

Given that the period of \text{cosec } x is 2 \pi, complete the table of values over the domain \left( - 2 \pi , 0\right):

x- \dfrac{7 \pi}{4}- \dfrac{3 \pi}{2}- \dfrac{5 \pi}{4}- \dfrac{3 \pi}{4}- \dfrac{\pi}{2}- \dfrac{\pi}{4}
\text{cosec } x
b

Sketch the graph of y = \text{cosec } x on the interval \left( - 4 \pi , 4 \pi\right).

23

Consider the table of values for \sec x in the interval \left[0, 2 \pi\right]:

x0\dfrac{\pi}{4}\dfrac{3 \pi}{4}\pi\dfrac{5 \pi}{4}\dfrac{7 \pi}{4}2 \pi
\sec x1\sqrt{2}- \sqrt{2}- 1- \sqrt{2}\sqrt{2}1
a

Given that the period of \sec x is 2 \pi, complete the table of values over the domain \left[ - 2 \pi , 0\right]:

x- 2 \pi- \dfrac{7 \pi}{4}- \dfrac{5 \pi}{4}- \pi- \dfrac{3 \pi}{4}- \dfrac{\pi}{4}0
\sec x1
b

Sketch the graph of y = \sec x on the interval \left[ - 4 \pi , 4 \pi\right].

24

Consider the graph of y = \text{cosec } x and the line y=\sqrt{2}:

a

When x = \dfrac{\pi}{4}, y = \sqrt{2}. Find the next positive x-value for which y = \sqrt{2}.

b

State the period of y = \text{cosec } x.

c

Find the smallest value of x greater than 2 \pi for which y = \sqrt{2}.

d

Find the first x-value less than 0 for which y = \sqrt{2}.

\frac{1}{4}π
\frac{1}{2}π
\frac{3}{4}π
\frac{5}{4}π
\frac{3}{2}π
\frac{7}{4}π
\frac{9}{4}π
x
-2
-1
1
2
y
25

Consider the graph of y = \sec x:

a

When x = \dfrac{\pi}{3}, y = 2. Find the next positive x-value for which y = 2.

b

State the period of y = \sec x.

c

Find the smallest value of x greater than 2 \pi for which y = 2.

d

Find the first x-value less than 0 for which y = 2.

\frac{1}{3}π
\frac{2}{3}π
\frac{4}{3}π
\frac{5}{3}π
x
-2
-1
1
2
y
26

Consider the graph of y = \cot x and the line y=\sqrt{3}:

a

When x = \dfrac{\pi}{6}, y = \sqrt{3}. Find the next positive x-value for which y = \sqrt{3}.

b

State the period of y = \cot x.

c

Find the smallest value of x greater than 2 \pi for which y = \sqrt{3}.

d

Find the first x-value less than 0 for which y = \sqrt{3}.

\frac{1}{2}π
\frac{3}{2}π
x
-2
-1
1
2
y
27

Consider the graphs of \text{cosec } x and \sec x in the interval \left[-\dfrac{\pi}{2}, 2 \pi\right]:

State the interval where \text{cosec } x \gt 0 and \sec x \lt 0.

\frac{1}{2}π
\frac{3}{2}π
x
-3
-2
-1
1
2
3
y
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Outcomes

0606C9.1

Solve problems involving the arc length and sector area of a circle, including knowledge and use of radian measure.

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