Question

A man on the top of a vertical observation tower observes a car moving at a uniform speed coming directly towards it. If it takes 12 minutes for the angle of depression to change from 30 degrees to 45 degrees , how long will the car take to reach the observation tower from this point? ,

Answer 1

Step-by-step explanation:

Let Let the uniform speed be x

Time taken by car to move distance x = 12 so

Distance travelled by car = speed ×time =12x

Let distance to reach foot of tower be y

Use tan 30 = p/b

1/√3= p/12x+y

12x+y/√3=p

Now for small triangle

Use tan 45 = p/b

1=p/y

P=y

Compare both values of p now

12x+y /√3=y

Y(1-√3)/-12=x

Hence found