Question:
A chimney 20 m high standing on the top of a building subtends an angle whose tangent is (1)/(6) at a distance 70 m from the foot of the building. The height of the building is
A chimney 20 m high standing on the top of a building subtends an angle whose tangent is (1)/(6) at a distance 70 m from the foot of the building. The height of the building is
Options:
- 50 m
- 60 m
- 20 m
- 40 m
- 50 m
- 60 m
- 20 m
- 40 m
Correct Answer: a)
Explanation:
‘ Let AB = H m be the building and CB be the chimney.
‘ tan = tana = Hix and ‘
tang = 2
Cc.
1 1 1
20m
def
! aA a! !
Pe———70m— A
‘ Now, tan = 1 i
‘ = tan(a — B) = 3
LE Ee ee EE EE EE Ee a a
(tana—tan 8) _ 1 !
i = Trwnawnp ©
H120
Lo -o(uEg)
Doing)
= 6 x Ell _ 4900, 20H 1 H?
1 = H? + 20H + 4900 — 8400 = 0
‘ -. H2 + 20H — 3500 = 0
= (H —50)(H +170) =0
! CH=
1 SL H=50m
153, !
‘ Let AB = H m be the building and CB be the chimney.
‘ tan = tana = Hix and ‘
tang = 2
Cc.
1 1 1
20m
def
! aA a! !
Pe———70m— A
‘ Now, tan = 1 i
‘ = tan(a — B) = 3
LE Ee ee EE EE EE Ee a a
(tana—tan 8) _ 1 !
i = Trwnawnp ©
H120
Lo -o(uEg)
Doing)
= 6 x Ell _ 4900, 20H 1 H?
1 = H? + 20H + 4900 — 8400 = 0
‘ -. H2 + 20H — 3500 = 0
= (H —50)(H +170) =0
! CH=
1 SL H=50m
153, !