Question

ICS-X
210 and 18° 30'. Calculate:
(1) the height of the cliff;
(ii) the height of the pillar
[Hint. Use tables to find tan 21° and tan 1830.
on the
ght of
Pillar
21°
Clim
18°30
200 m
Boat
Fig. 17.20
HEIGHTS AND DISTANCES
9. In Fig. 17.20, from a boat 200 m away from a vertical
cliff the angles of elevation of the top and the foot of
a vertical concrete pillar at the edge of the cliff are​

Answer 1

Answer:

Let height be y ΔOAC

tanθ=

B

P

tanβ=

OA

CA

tanβ=

x

y+h

(y+h)→ Let AB, AB+BC

Let OA→ x

x=[

tanβ

y+x

]

Consider ΔOAB

tanα=

x

y

=

Base

perpendicular

x=

tanα

y

tanα

y

=

tanβ

y+h

ytanβ=tanαy+tanαh

ytanβ−tany=tanαh

y(tanβ−tanα)=tanαh

y=

tanβ−tanα

htanα

This