Question

27. From a point on the ground, the angles of elevation of the top and bottom of
a transmission tower fixed at the top of a 20m high building are 60' and 45°
respectively. Find the height of the transmission tower.
0-60°
B
20m
009
459
D
C
-
SIOP​

Answer 1

Answer:

Let DC be the tower and BC be the building. Then,

∠CAB=45

o

,∠DAB=60

o

,BC=20 m

Let height of the tower, DC=h m.

In right △ABC,

tan45

o

=

AB

BC

1=

AB

20

AB=20 m

In right △ABD,

tan60

o

=

AB

BD

3

=

20

h+20

h=20(

3

−1) m