Question

An aeroplane is flying at a height of 300 above the ground. Flying at this

height, the angles of depression from the aeroplane of two points on both

banks of a river in opposite directions are 45° and 60° respectively. Find the

width of the river.​

Answer 1

Answer:

Let A be the aeroplane BD is the length of the river

tan45o =(AC/BC)

1= 300/BB

BC=300m

tan60o = (AC/CD)

root3 = 300/CD

CD=( 300/root 3)×(root 3/root 3)

=(300 root3)/root 3

=100root3

=1.732×100=173.2

width of river =BC+CD=300+173.2=473.2m