
RS Aggarwal Solutions for Class 10 Maths Chapter 14 Exercise 14: RS Aggarwal Solutions for Class 10 Maths Chapter 14 on Height and Distance, Exercise 14, provide detailed explanations and step-by-step solutions to problems involving trigonometric concepts. This chapter focuses on practical applications of trigonometry to calculate heights and distances, using angles of elevation and depression.
The solutions help students understand how to apply trigonometric ratios to real-life situations, such as finding the height of a building or the distance between two objects. These solutions are designed to enhance students problem-solving skills and prepare them for their board exams by providing clear, concise, and accurate methods to tackle various trigonometric problems.RS Aggarwal Solutions for Class 10 Maths Chapter 14 Exercise 14 PDF
Given
Height of kite from ground ,
A
B
=
75
m
The inclination of string with ground
θ
=
60
o
Length of string,
L
=
A
C
If we represent the above data in form of the figure as shown it forms a right angle triangle
Δ
A
B
C
Here,
sin
θ
=
o
p
p
o
s
i
t
e
s
i
d
e
h
y
p
o
t
e
n
u
s
e
sin
60
o
=
A
B
A
C
√
3
2
=
75
L
L
=
150
√
3
m
L
e
n
g
t
h
o
f
s
t
r
i
n
g
,
L
=
150
√
3
m
=
150
1.732
=
86.60
m
CD is the height of the flag and suppose the height of tower BC = h
Now consider right triangle ABD , we have;
tan 60° = BD/AB = BD/120⇒√3 = BD/120⇒BD = 120√3
Also considering right triangle ABC, we have;
tan 45° = BC/AB = h/120⇒1 ⇒ h=120
So height of flag = BD - BC = 120√−120 = 120(3√−1) = 120×0.732 = 87.84
Therefore height of the flag is 87.84 m.
Q.
From the top of a 7-metre-high building, the angle of elevation of the top of a cable tower is
60
∘
and the angle of depression of its foot is
45
∘
. Determine the height of the tower. [Use
√
3
=
1.732
]
Let AB be the building and CD be the tower such that <EAD = 60
o
and <EAC = <ACB = 45
o
Now, In triangle ABC, tan 45 = 1 = AB/BC
So, AB = AE = 7 m
Again in triangle AED,
tan 60 =
Let CD be the tower.
Suppose BC = x m and CD = h m.
Given, ∠ADE = 30° and ∠CBD = 60°.
∠DAC = ∠ADE = 30° (Alternate angles)
In ΔACD,
Let the height of the tower be h cm.
Now, In
△
P
A
B
tan
60
o
=
A
P
A
B
⇒
√
3
=
h
A
B
⇒
A
B
=
h
√
3
−
−
−
−
(
1
)
And, In
△
P
C
D
tan
30
o
=
P
D
C
D
⇒
1
√
3
=
h
−
10
C
D
⇒
C
D
=
√
3
(
h
−
10
)
−
−
−
−
(
2
)
Since, AB = CD, So, equation (2) becomes,
A
B
=
√
3
(
h
−
10
)
−
−
−
−
(
3
)
Equating equation (1) and (3), we get,
h
√
3
=
√
3
(
h
−
10
)
h
=
3
(
h
−
10
)
2
h
=
30
=
h
=
15
m
Hence, the height of the tower will be 15 m
Q.
A man on the deck of a ship, 16 m above water level, observes that the angles of elevation and depression respectively of the top and bottom of a cliff are
60
∘
a
n
d
30
∘
. Calculate the distance of the cliff from the ship and height of the cliff. [Take
√
3
=
1.732.
]
In YRQ, we have
AA´ and BB´ denote the height of the plane from the ground.
∴ AA´ = BB´ = 2500 m
From
△
OAA´
t
a
n
45
o
=
A
A
′
O
A
′
1
=
A
A
′
O
A
′
O
A
′
=
A
A
′
=
2500
m
From
△
OBB´
t
a
n
30
o
=
B
B
′
O
B
′
1
√
3
=
B
B
′
O
B
′
O
B
′
=
√
3
B
B
′
=
2500
√
3
m
Distance covered by the plane from A to B is AB or A´B´
⇒ A´B´ = OB´ – OA´
=
(
2500
√
3
−
2500
)
=
2500
(
√
3
−
1
=
2500
(
1.73
−
1
=
2500
×
0.73
=
1825
m
Time taken by the plane in moving from A to B = 15 seconds
Speed of the plane
=
1825
15
=
121.66
m
s
−
1
Q.
The angle of elevation of the top of a tower from a point on the same level as the foot of the tower is
30
∘
. On advancing 150 m towards the foot of the tower, the angle of elevation becomes
60
∘
. Show that the height of the tower is 129.9 metres. [Take
√
3
=
1.732.
]
Use trigonometric ratios in the
△
ABD,
t
a
n
60
o
=
h
a
√
3
=
h
a
h
=
√
3
a
−
−
−
−
(
1
)
Similarly using trigonometric ratios in the
△
ABC, we get,
t
a
n
30
o
=
h
a
+
150
1
√
3
=
h
a
+
150
√
3
h
=
150
+
a
−
−
−
−
(
2
)
Use equation(1) in equation (2),
a = 75 -----(3)
Put the value of a in equation(1) to get the value of h,
h
=
75
×
√
3
=
75
×
1.73
=
129.9
m
Therefore the height of the tower is 129.9 m.
Hence Proved
Q.
As observed from the top of a lighthouse, 100 m above sea level, the angle of depression of a ship, sailing directly towards it, changes from
30
∘
t
o
60
∘
. Determine the distance travelled by the ship during the period of observation. [Take
√
3
=
1.732.
]
Given, AB= 100 m
Let x be the distance travelled by the ship during the period of observation. i.e., CD = x m
I
n
△
A
B
D
t
a
n
60
o
=
A
B
B
D
⇒
√
3
=
100
B
D
⇒
B
D
=
100
√
3
−
−
−
−
−
(
1
)
I
n
△
A
B
C
t
a
n
30
o
=
A
B
B
C
⇒
1
√
3
=
100
B
D
+
C
D
⇒
1
√
3
=
100
B
D
+
x
⇒
B
D
+
x
=
100
√
3
−
−
−
−
(
2
)
Put (1) in (2),
100
√
3
+
x
=
100
√
3
x
=
100
√
3
−
100
√
3
=
300
−
100
√
3
=
200
√
3
=
115.47
m
[Take
√
3
=
1.732
]
Hence, the distance travelled by the ship during the period of observation is 115.47 m
In
△
ABD,
t
a
n
30
o
=
2.5
A
B
1
√
3
=
2.5
A
B
A
B
=
2.5
×
√
3
=
2.5
×
1.732
=
4.33
In
△
BDC,
t
a
n
45
o
=
2.5
B
C
1
=
2.5
B
C
B
C
=
2.5
Width of river = AB + BC
= 4.33 + 2.5 = 6.83 meter
Q.
The angles of elevation of the top of a tower from two points at distances of 4 m and 9 m from the base of the tower and in the same straight line with it are complementary. Show that the height of the tower is 6 metres.
Let height of the tower be h m.
Given, the angles of elevation of the top of tower from the two points are complementary.
∴ ∠ACB = θ and ∠ADB = 90 – θ
In ∆ABC,
