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Stage 5.1-2

8.04 Finding an angle

Worksheet
Inverse trigonometric functions
1

Find the value of the following expressions, correct to the nearest degree:

a
\sin^{-1}(0.7035)
b
\cos^{-1}(0.4447)
c
\tan^{-1}(0.5085)
d
\sin^{-1}(0.2734)
e
\cos^{-1}(0.6484)
f
\tan^{-1}(8.1519)
g
\sin^{-1}(0.8176)
h
\cos^{-1}(0.7035)
2

For each of the following, find \theta to the nearest degree:

a

\sin \theta = 0

b

\cos \theta = 0

c

\tan \theta = 0

d

\sin \theta = 1

e

\cos \theta = 1

f

\tan \theta = 1

g

\cos \theta = 0.5

h

\sin \theta = 0.906

i

\sin \theta = 0.210

j

\cos \theta = 0.296

k

\cos \theta = 0.899

l

\tan \theta = 0.734

m

\tan \theta = 1.739

n

\tan \theta = 0.869

o

\tan \theta = 2.2

p

\tan \theta = \dfrac{9}{10}

q

\sin \theta = \dfrac{43}{47}

r

\cos \theta = \dfrac{31}{53}

s

\tan \theta = \dfrac{31}{71}

t

\tan \theta = \dfrac{41}{31}

3

For each of the following, find \theta to the nearest tenth of a degree:

a

\sin \theta = 0.8613

b

\cos \theta = 0.4825

c

\tan \theta = 8.958

Unknown angles
4

For each of the following triangles, find the value of the pronumeral, correct to the nearest degree:

a
b
c
d
e
f
g
h
i
j
5

Consider the following diagram:

a

Find the value of x, correct to two decimal places.

b

Find the value of x, correct to the nearest degree.

Applications
6

An isosceles triangle has equal side lengths of 10 \text{ cm} and a base of 8 \text{ cm} as shown.

Calculate the size of angle A to one decimal place.

7

Consider the given figure:

Find the following, rounding your answers to two decimal place:

a

x

b

y

c

z

8

Consider the following figure:

Find x and y correct to one decimal place.

9

Find x, the angle of depression from point B to point C in the diagram below:

Round your answer to two decimal places.

10

Consider the following figure:

a

Find the size of angle x in degrees, correct to two decimal places.

b

Find the size of angle y in degrees, correct to two decimal places.

11

Consider the given diagram:

a

Find the length of AC, to two decimal places.

b

Find the size of \angle ACB.

c

Find the size of \angle ACD.

d

Hence, find the length of CD, to one decimal place.

12

A suspension bridge is being built. The top of the concrete tower is 35.5 \text{ m} above the bridge and the connection point for the main cable is 65.9 \text{ m} from the tower.

Assume that the concrete tower and the bridge are perpendicular to each other.

a

Find the length of the cable to two decimal places.

b

Find the angle the cable makes with the road to two decimal places.

13

During rare parts of Mercury and Venus' orbit, the angle from the Sun to Mercury to Venus is a right angle, as shown in the diagram:

The distance from Mercury to the Sun is 60\,000\,000\text{ km}. The distance from Venus to the Sun is 115\,000\,000\text{ km}.

What is the angle \theta, from Venus to the Sun to Mercury? Round your answer to the nearest degree.

14

A 13.7 \text{ m} long string of lights joins the top of a tree to a point on the ground. If the tree is 3.7 \text{ m} tall, find \theta, the angle the string of lights would make with the tree. Round your answer to two decimal places.

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Outcomes

MA5.1-10MG

applies trigonometry, given diagrams, to solve problems, including problems involving angles of elevation and depression

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