A 6-FOOT SPRUCE TREE IS PLANTED 15 FEET FROM A LIGHTED STREETLIGHT WHOSE STREETLIGHT IS 18 FEET ABOVE THE GROUND. HOW MANY FEET IS THE SHADOW OF THE TREE?
2007-09-18 14:46:39 · 6 answers · asked by mexicanmorra_12692 1 in Science & Mathematics ➔ Mathematics
6 ___15__ >18
This is a proportion using heights and lengths of triangles.
Imaging the tree and its shadow as one triangle (ignore the hypotenuse). The other will be the height of the light and the distance from it to the end of the trees shadow.
Lets call the shadow x.
So the tree is to its shadow as the pole is to the distance to the tree plus its shadow.
6/x = 18/(15+x)
Now solve for x
6 = 18x/(15+x)
90 + 6 x = 18x
12x = 90
x = 7.5 feet
2007-09-18 14:50:22 · answer #1 · answered by ignoramus 7 · 0⤊ 1⤋
similar triangles
as 6/18 = x/15
therefore (6 x 15)/8 ='s 11.25 m's
2007-09-18 14:51:20 · answer #2 · answered by Suki 4 · 0⤊ 0⤋
actually suki is wrong its 7.5 ft
its similar triangles so its 18/15+x = 6/x
X is the length of the shadow and you cross multiply and u get 7.5ft
2007-09-18 14:58:57 · answer #3 · answered by dauntless 1 · 0⤊ 0⤋
how long is the shadow of the street light
2007-09-18 14:50:36 · answer #4 · answered by Anonymous · 0⤊ 1⤋
i think three maybe i don't know i am only 12
2007-09-18 14:51:05 · answer #5 · answered by kittyc07 1 · 0⤊ 1⤋
that doesnt really make sense. it depends where the sun is...
2007-09-18 14:50:37 · answer #6 · answered by Anonymous · 0⤊ 1⤋