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If a 6 foot tree is planted 15 feet from a lighted streetlight whose lamp is 18 feet above the ground how many feet long is the shadow of that tree?
Wiki User
∙ 13y ago
First you need a labeled picture.
>o<
| .
| .
| .
18 ft | .
| 6 ft ^ .
| | .
-------------- *****
15 ft x
In this picture the " . . ." line represents the light as it goes down from the lamp to the tree. The **** line represents the shadow of the tree.
Inside this picture there are two right triangles: a big one and a small one. The big one has 18 ft as its up-and-down side and 15 + x as is right-to-left side. The little one has the tree (6 ft) as its up-and-down side and the tree's shadow (which has length 'x') as its right-to-left side.
As you can see the little triangle is INSIDE the big triangle. These two triangles are SIMILAR because although they are different sizes, their angles are the same. (For example, the street lamp meets the ground at 90 degrees, and the tree also meets the ground at 90 degrees).
Because the triangles are similar we know the ratios of their sides must be equal:
BIG triangle LITTLE triangle
up-and-down 18 6
------- = -------
right-to-left 15+x x
Cross multiply 18x = 6(15 + x)
18x = 90 + 6x
12x = 90
x = 90/12 = 7.5 ft
Therefore, the shadow must be 7.5 ft long.
Wiki User
∙ 13y ago
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How long in feet would the shadow be for an object which is 18.6 feet tall?
In addition to the height of the object, the length of its shadow depends on a few other things that are not described in the question. -- Is the object standing straight upright ? -- Is the shadow cast on the ground or on sometheing else? -- If on the ground, is the ground level ? -- What is the altitude (angle) of the sun ?
An adult and a child are standing together in a park If the adult is 6 feet tall and casts a shadow on the ground that is 4 feet long how long will the child's shadow be if she is 4 feet 6 inches tall?
3 feet
Is the length of your shadow the same as your height?
No. Only if the ground is level and the light source is very far away and at a 45 degree angle.
How long of a shadow would a light of 30 feet off the ground make when shining on an object 10 feet tall that is 20 feet away from the light?
The shaddow would be 6.7 feet long (assuming flat ground)
How did human beings know that the earth was a sphere before the use of satellites?
Some very wise man noticed that the shadow cast from a stick placed vertically in the ground was a different angle at exactly noon than the angle of shadow cast at exactly noon from a vertically placed stick in the ground at a location further north. By employing mathematics, he was able to deduce that the earth is in fact, roundish.
Why do shadows change shape in the course of the day?
Next time you go for a walk at night, walk under a streetlight, and watch your shadow on the ground. While you're watching your shadow, think about how the sun moves across the sky during the day.
What direction does the shadow point at night under a street light?
Directly under the streetlight there is no shadow. If an object is not directly under the light then the shadow starts at the base of the object and points away from the light.
Where is he going see his shadow?
On the ground
Where is the shadow cast relation to the sun?
The nearer the sun is to the ground, the longer the shadow casted.
Did the ground hog see his shadow in 2011?
no
What causes a strange shadow on the ground?
the sun
Why does shadow walk with us?
Because your shadow is caused by your body coming between the ground and the Sun.
What does a shadow mean?
Stand in the sunshine, back to the sun. That flat person on the ground in front of you is your shadow.
Why we get shadow on sunny day?
Stand with your back to the Sun, and look at your shadow on the ground. Your shadow is created because your body is blocking out the sunlight.
Why is there no shadow of the tree on the ground at 8pm?
as there is no sunlight at 8pm,and shadow is formed when light can not pass through that object casting shadow and if u throw light on tree it will not cast shadow on the ground as it only can happen before sunset.....
What do you call the object that do not cast a shadow?
ground ot
Why the shadow of flying bird is not seen on the ground even though it is opaque?
If you see a bird but do not see a shadow on the ground, it is probably because of the angle the light is coming from. If you drew an imaginary line form the source of light, (probably the sun) through the bird, you would find the shadow of the bird where the line touched the ground. If there is no light, the bird cannot make a shadow.
