the angle of elevation of the top of the tower from point A on the ground is 30 .on moving a distance of 20 m towards the foot of the tower to a point B .the angle of elevation increase to 60 find the hight of the tower and the distance of the tower from the point A (take root 3 = 1.732).
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From ΔABC:
tan (θ) = opp/adj
tan (30) = BC/AB
BC = AB tan (30)
From ΔBCD:
tan (θ) = opp/adj
tan (60) = BC/BD
BC = BD tan (60)
Equate the 2 equations:
AB tan (60) = BD tan (30)
Define x:
Let BD = x
AB = x + 20
Solve x:
AB tan (30) = BD tan (60)
(x + 20) tan (30) = x tan (60)
x tan (30) + 20 tan (30) = x tan (60)
x tan (60) - x tan (30) = 20 tan (30)
x ( tan (60) - tan (30) ) = 20 tan (30)
x = 20 tan (30) ÷ ( tan (60) - tan (60) )
x = 10 m
Find the distance:
Distance = 10 + 20 = 30 m
Find the height:
tan (θ) = opp/adj
tan (60) = BC/10
BC = 10 tan (60) = 10√3 m
Answer: Distance = 30 m and height = 10√3 m
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Hope it helps you dude......
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