A 5.5 feet tall person standing 25 feet away from the streetlight casts a shadow that is 10 feet long. How tall is the streetlight?

Answer 1

19 1/4 feet high street light

construct two similar right triangles

set their side ratios equal

5.5/10 = h/(10+25)

h/35= 1.1/2

2h = 38.5

h = 38.5/2 = 19.25

street lamp height = 19 1/4 feet

it helps to draw a rough sketch or diagram, maybe alone or on a graph

base of one right triangle is 10, height 5.5

base of the bigger right triangle is 10+25 = 35, height is h

set height/base ratios of the two triangles equal

5.5/10 = h/35, solve for h

5.5 is a little larger than half of 10

so h will be a little larger than half of 35