Question

1)An aeroplane is flying at a height of 300 m 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 river is ​

Answer 1

Sol:- here , given aeroplane is flying at a height of a 300 mtr above the ground ,Flying at this height, the angles of depression from the aeroplane of two points on both sides of a river in opposite directions are 45° and 60° respectively.

here, √3=1.732

so, according to question,

From first triangle,

tan 60°= 200/x

√3= 200/x

x= 200/√3mtr.

From second triangle,

tan45°= 200/y

1= 200/y

y= 200.

Width of the river=x+y=

200/√3 + 200= 200 ( 1/√3 + 1)= 200(1+√3)/√3 mtr.

therefore, the width of the river = 200(1+√3)/√3 metre.

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