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7.10 Trigonometry in 3D

Worksheet
Trigonometry in 3D
1

All edges of the following cube are 7 \text{ cm} long:

a

Find the exact length of the following:

i

EG

ii

AG

b

Find the following angles to the nearest degree:

i

\angle EGH

ii

\angle EGA

iii

\angle AHG

iv

\angle AGH

2

A square prism has sides of length 3 \text{ cm}, 3 \text{ cm} and 14 \text{ cm} as shown in the diagram:

a

If the diagonal HF has a length of z \text{ cm}, find the value of z to two decimal places.

b

If the size of \angle DFH is \theta \degree, find \theta to two decimal places.

3

The box have a triangular divider placed inside it, as shown in the diagram:

a

If z = AC, find the value of z to two decimal places.

b

Find the area of the divider correct to two decimal places.

4

A triangular prism has dimensions as shown in the diagram:

a

Find the size of \angle AED, correct to two decimal places.

b

Find the exact length of CE.

c

Find the exact length of BE.

d

Find the size of \angle BEC, correct to two decimal places.

e

Find the exact length of CX.

f

Find the size of \angle BXC, correct to two decimal places.

5

Consider the given rectangular prism:

a

Find the length x.

b

Hence, find the length of the prism's diagonal y.

c

Find the angle \theta to the nearest degree.

6

Consider the cube as shown:

a

Find the size of:

i

\alpha

ii

\beta

iii

\gamma

b

Calculate the exact length of x.

c

Calculate the exact length of y.

d

Hence, find the angle \theta to the nearest degree.

7

A 25 \text{ cm }\times 11 \text{ cm }\times 8 \text{ cm} cardboard box contains an insert (the shaded area) made of foam:

a

Find the exact length b of the base of the foam insert.

b

Find the area of foam in the insert, rounded to the nearest square centimetre.

c

Find the value of \theta to the nearest degree.

8

A tree stands at the corner of a square playing field. Each side of the square is 130 \text{ m} long. At the centre of the field the tree subtends an angle of 22 \degree as shown:

a

Find the distance from the tree to the centre of the field. Round your answer to two decimal places.

b

Find the height of the tree. Round your answer to two decimal places.

c

Find the size of the angle subtended by the tree at the corner of the field opposite the tree. Round your answer to the nearest minute.

d

Find the size of the angle subtended by the tree at an adjacent corner of the field. Round your answer to the nearest minute.

9

A, \,C, and X are three points in a horizontal plane and B is a point vertically above X as shown in the diagram:

Find the following lengths to the nearest metre:

a

BC

b

XB

10

A cone has radius 7\text{ cm} and a slant height of 13\text{ cm}:

Find the vertical angle, \theta, at the top of the cone in degrees and minutes.

11

The following is a right pyramid on a square base with side length 12 \text{ cm}. The edge length VA is 23 \text{ cm}.

a

If z = AW, calculate the length z.

b

If \theta = \angle VAW, find the value of \theta.

12

The following pyramid has a square base with side length 8 \text{ cm}, and all slanted edges are 12 \text{ cm} in length:

a

Find the exact length of MD.

b

Find the size of \angle PDM, correct to two decimal places.

c

Find the exact height of the pyramid, MP.

d

Find the length of MN.

e

Find the exact length of PN.

f

Find the size of \angle PNM, correct to two decimal places.

g

Find the size of \angle PDC, correct to two decimal places.

13

This triangular prism shaped box needs a diagonal support inserted as between A and F as shown:

AB = 19, \, BD = 30 and DF = 43. find the length of AF to two decimal places.

14

From a point 15\text{ m} due north of a tower, the angle of elevation of the tower is 32 \degree.

a

Find the height of the tower h. Round your answer to two decimals places.

b

Find the size \theta of the angle of elevation of the tower at a point 20\text{ m} due east of the tower. Round your answer to the nearest degree.

15

A pole is seen by two people, Jenny and Matt:

a

Matt is x\text{ m} from the foot of the pole. Find x to the nearest metre.

b

Find the height of the pole h to the nearest metre.

16

Two straight paths to the top of a cliff are inclined at angles of 24 \degree and 21 \degree to the horizontal:

a

If path A is 115\text{ m} long, find the height h of the cliff, rounded to the nearest metre.

b

Find the length x of path B, correct to the nearest metre.

c

Let the paths meet at 46 \degree at the base of the cliff. Find their distance apart, y, at the top of the cliff, to the nearest metre.

17

A pyramid has a square base with side length 14 \text{ m} and a vertical height of 24 \text{ m}:

a

Find the length of the edge AE. Round your answer to one decimal place.

b

Find the size of \angle BEA, to the nearest minute.

18

Two buoys, A and B, are observed from a lookout at the top of a 130 \text{ m} high cliff. The bearing of buoy A is 337 \degree and its angle of depression is 3 \degree. The bearing of buoy B is 308 \degree and its angle of depression is 5 \degree:

a

Find the distance, to the nearest metre, from buoy A to the base of the cliff.

b

Find the distance from buoy B to the base of the cliff, to the nearest metre.

c

Find the distance between the two buoys, to the nearest metre.

19

In the tetrahedron shown, the angles \angle VBC, \, \angle VBA, and \angle ABC are all right-angles.

a

Find the following distances, to two decimal places:

i

VA

ii

VC

iii

AC

b

Find the size of angle \angle VCA. Round your answer to the nearest minute.

20

Roald is standing at point P and observes two poles, AB and CD, of different heights. P, \, B, and D are on horizontal ground:

From P, the angles of elevation to the top of the poles at A and C are 29 \degree and 18 \degree respectively. Roald is 16 \text{ m} from the base of pole AB. The height of pole CD is 7 \text{ m}.

a

Calculate the distance from Roald to the top of pole CD, to two decimal places.

b

Calculate the distance from Roald to the top of pole AB, to two decimal places.

c

Calculate the distance between the tops of the poles, to two decimal places.

21

Point A is due north of a tower, and has an angle of elevation to the top of the tower of 51 \degree. Point B is 100 \text{ m} from point A on a bearing of 120 \degree. The angle of elevation from point B to the top of the tower is 25 \degree.

Find the height of the tower to the nearest metre.

22

A room measures 5 \text{ m} in length and 4 \text{ m} in width. The angle of elevation from the bottom left corner to the top right corner of the room is 57 \degree.

a

Find the exact distance from one corner of the floor to the opposite corner of the floor.

b

Find the height of the room. Round your answer to two decimal places.

c

Find the angle of elevation from the bottom corner of the 5 \text{ m} long wall to the opposite top corner of the wall. Round your answer to two decimal places.

d

Find the angle of depression from the top corner of the 4 \text{ m} long wall to the opposite bottom corner of the wall. Round your answer to two decimal places.

23

A and B are two positions on level ground. From an advertising balloon at a vertical height of 740 \text{ m}, \, A is observed in an easterly direction and B at a bearing of 159 \degree. The angles of depression of A and B, as viewed from the balloon, are 30 \degree and 20 \degree, respectively.

a

Find the distance from point A to the point directly below the advertising balloon, to the nearest metre.

b

Find the distance from point B to the point directly below the advertising balloon, to the nearest metre.

c

Find the distance between points A and B, to the nearest metre.

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Outcomes

VCMMG370 (10a)

Apply Pythagoras’ theorem and trigonometry to solving three-dimensional problems in right-angled triangles.

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