Q. 114.3( 201 Votes )

# A TV tower stands vertically on a bank of a canal. From a point on the other bank directly opposite the tower, the angle of elevation of the top of the tower is 60°. From another point 20 m away from this point on the line joining this point to the foot of the tower, the angle of elevation of the top of the tower is 30° (see Fig. 9.12). Find the height of the tower and the width of the canal

Answer :

According to this figure:

CD = 20 m,

∠ACB = 60°,

∠ ADB = 30°,

AB = ? and BD = ?

In Δ ABC,

where p = perpendicular and b = base of triangle

In Δ ABD,

where p = perpendicular and b = base of triangle

𝐹rom (i) and (ii),

Using the value of BC in (i) we get;

AB = 10√3 m which is the height of the tower

Width of canal = 10 m

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