Question

please give me full solution

Answer 1

Let position of aeroplane be A
B and C be 2 points on 2 banks of river such that angle of depression at B and C are 45° and 60°respectively.
In rt. Angled triangle ABD
Tan45°=AD/BD
1=200/x
X=200m-------'1'

In rt. Angled triangle ACD
Tan60°=AD/CD
3^1/2=200/y
Y=200/3^1/2--------'2'


Adding 1 and 2
X+y= 200(1+1/3^1/2)
X+y=200(3^1/2+1)/3^1/2
X+y=315.4m

Hence width of river =315.4 m
Hope it helps you....