Question
A man of height 1.5 meters walk away from a 5-meter lamppost at a speed of 1.8 m/s. Find the rate at which his shadow is increasing in length.
Answers
How far away is he?
Otherwise I can only give you the function.
man is p from pole (we need this)
shadow tip is s from pole
we want ds/dt
s/5 = (s-p)/1.5
1.5 s = 5 s - 5 p
3.5 s = 5 p
s = 1.43 p
ds/dt = 1.43 dp/dt
but dp/dt = 1.8
so
ds/dt = 2.57 m/s
Otherwise I can only give you the function.
man is p from pole (we need this)
shadow tip is s from pole
we want ds/dt
s/5 = (s-p)/1.5
1.5 s = 5 s - 5 p
3.5 s = 5 p
s = 1.43 p
ds/dt = 1.43 dp/dt
but dp/dt = 1.8
so
ds/dt = 2.57 m/s
iwan stands 4 metres away from his school and measured the angle of elevation of the roof to be 67 degrees if Iwan is 1.7 meters tall calculate the height of the school