Question

a man standing on the on the bank of the river observes that the angle of elevation of the top of the building of an organisation working for conservation of wildlife standing on the opposite bank is 60.when he moves 40 m away from the bank he finds that the angle of elevation is 45.find the height of the building and the width of the river

Answer 1

let the height h ,and width of the river x
then,
tan(60)=h/x

3^1/2=h/x
h=3^1/2x
then,
tan(45)=h/40+x
1=h/40+x
40+x=h
40+x=3^1/2x
40=(3^1/2x-x)
40=(3^1/2-1)x
x=(40/3^1/2-1)
x=54.64101615