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3.03 Finding unknown angles

Worksheet
Unknown angles
1

Find the acute angle \theta to the nearest degree if:

a

\sin \theta = 0.1

b

\cos \theta = 0.73

c

\tan \theta = 1.3

d

\cos \theta = \dfrac{4}{9}

e

\tan \theta = \dfrac{4}{9}

f

\sin \theta = \dfrac{35}{45}

g

\cos \theta = 0.5216

h

\tan \theta = 2.694

i

\sin \theta = 0.7458

2

Use the tangent ratio to find the value of the pronumeral, correct to the nearest degree:

a
b
c
d
3

Find the value of the pronumeral in each triangle to the nearest degree:

a
b
c
d
e
f
4

Consider the given figure:

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

a

x

b

y

c

z

5

Find the value of \theta to the nearest degree in the following figure:

6

Consider the following figure:

a

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

b

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

7

Consider the following figure:

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

a

x

b

y

8

In a right-angled triangle, the lengths of the opposite and adjacent sides of angle x can be written in the ratio 4:3. Solve for the value of x, to the nearest degree.

9

Find the value of \theta in this triangle. Round your answer to the nearest degree.

Applications
10

The straight line segment makes an angle of A\degree with the positive x-axis:

Find the size of angle A, correct to the nearest degree.

1
2
3
4
5
6
7
8
x
1
2
3
4
5
6
7
8
y
11

A ship dropped anchor off the coast of a resort. The anchor fell 83\text{ m} to the sea bed. During the next 4 hours, the ship drifted 105\text{ m}.

Find x, the angle between the anchor line and the surface of the water, to the nearest degree.

12

The person in the picture sights a paraglider above him.

If the angle the person is looking at is a, find a to two decimal places.

13

During a particular time of the day, a tree casts a shadow of length 24\text{ m}. The height of the tree is estimated to be 7\text{ m}.

Find the angle \theta, formed by the length of the shadow and the arm extending from the edge of the shadow to the top of the tree. Round your answer to two decimal places.

14

A boy flying his kite releases the entire length of his string which measures 27\text{ m}, so that the kite is 18\text{ m} above him.

If the angle the string makes with the horizontal ground is \theta, find \theta to two decimal places.

15

A slide casts a shadow 5.66 \text{ m} along the ground. The distance between the tip of the shadow and the top of the slide is 7.84\text{ m}.

Find \theta to two decimal places.

16

In the diagram, a string of lights joins the top of the tree to a point on the ground 23.9 \text{ m} away. If the angle that the string of lights makes with the ground is \theta \degree, find \theta to two decimal places.

17

A ladder measuring 1.65 \text{ m} in length is leaning against a wall.

If the angle the ladder makes with the wall is y \degree, find y to two decimal places.

18

A ladder measuring 2.36 \text{ m} in length is leaning against a wall.

If the angle the ladder makes with the ground is y \degree, find the value of y to two decimal places.

19

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 two decimal places.

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Outcomes

MS2-12-3

interprets the results of measurements and calculations and makes judgements about their reasonableness, including the degree of accuracy and the conversion of units where appropriate

MS2-12-4

analyses two-dimensional and three-dimensional models to solve practical problems

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