Related rates question, shadow

[shanshan]

Homework Statement

A man 6m tall walks away from a light 10m above the ground. If his shadow lengthens at a rate of 2m/s, how fast is he walking?

Homework Equations

The Attempt at a Solution

I have nothing.

 

[cronxeh]

Using similar triangles you can find the relationship between the shadow length (B) and distance away from pole (A).


Keeping in mind that you are given dB/dt and asked to find dA/dt

 

[shanshan]

but how can i use similar triangles if i only have one of the dimensions of the triangle?

 

[cronxeh]

but how can i use similar triangles if i only have one of the dimensions of the triangle?

Look at the picture I attached. The relationship between ratios is constant, therefore the relationship between speed of man and length of shadow is constant

 

[shanshan]

ahhhh and the light goes on. thankyou!