Question

11. 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 joing
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 1

Answer:

Let the height of tower(BA)=hm

BC=xm

DB=20+x

angleABC=60°

angleABD=30°

In right angled triangleABC

BA/BC=tan60°

h/x=अंडर रूट 3

h=xअंडर रूट 3

AB/BD=tan30°

h/20+अंडर रूट 3 =1/अंडर रूट 3

h×अंडर रूट 3 =20×x

h=20+x/ अंडर रूट 3

x×अंडर रूट 3 ×अंडर रूट 3=20+x

3x=20+x

3x-x=20

2x=20

x=20/2

x=10m