A 5-ft man is standing 80ft from a street light. If the man's shadow is 40ft, determine the height of the street light.

Answer 1

Draw and labrel a diagram.

h represents the height of the lamp

5 : 40 :: h : 120

40h = 5(120)

Can you solve for h and answer?

Answer 2

Hello, thank you for taking the time to post your question!

The underlying concept that you want to use here is similar triangles … meaning that the proportion between these will be the same. What that means is that you can set up the equation

5/40 = height/120 based on the information given in the question

Solving that algebraically for the value of the height I get

Height = 120 x 5/40 = 15

Meaning that the height of the street light is 15 feet

I hope that helps get you moving in the right direction! Feel free to reach out if you have any additional questions beyond that :)

Answer 3

x/(80+40)=5/40

x=15 feet high street light

there are 2 similar right triangles

height to base ratios of the two triangles are the same

x/120 = 5/40

15/120 =5/40 = 1/8

length from tip of the shadow to bottom of the street light = 80+40= 120 feet

length from tip of the shadow to bottom of the man = 40 feet