At a particular time, a tree casts shadows 29meters long on horizontal ground. At the same time, a vertical pole 3meters high casts a shadow 4meter long.
How do I calculate the height on the tree to the nearest meter?
what should I do first? Im lost! Please help if you can. Thanks.
2007-11-29 07:13:16 · 13 answers · asked by carmenclassof06 4 in Science & Mathematics ➔ Mathematics
Well, that's like saying, x is to 29 as 3 is to 4.
29 / 3 * 4 = 21.75 --> 22
2007-11-29 07:17:53 · answer #1 · answered by Sarah 4 · 0⤊ 1⤋
I Love math!
It is a problem of relative ratio.
Let the letter x represent the unknown height of the tree.
So the problem can be stated...
a 3 meter pole is to a 4 meter shadow
as an x meter tree is to a 29 meter shadow.
The numbers would look like this...
3/4 = x/29
Now, multiply both sides of the equation by 29, to get the x by itself...
29 times 3/4 = x
or
87/4 = x
Now it's easy!
87 divided by 4 is 21.75.
So x = 21.75.
Just round to the nearest meter to get
22 meters.
Good Luck!
I hope this helps!
2007-11-29 15:32:21 · answer #2 · answered by troydowning 5 · 0⤊ 0⤋
To calculate, I would use ratios. Since a pole 3 meters high cast a 4 meter shadow, the ratio is 3:4...
Let x be the height of the tree...
x:29..
From here, I would cross multiply
3:4
x:29
29*3 = 87...
87/4= about 22 meters..
I hope this helped!!! :-)
2007-11-29 15:25:26 · answer #3 · answered by rihim77 2 · 0⤊ 0⤋
its a proportion.
so set it up like this: (pole hight over shadow length)
x ....... 3
----- = ------
29 ....... 4
then just do the "butterfly" multiplication... [x times 4, 29 times 3]
so you get 4x=87
then just divide by four on both sides
so you get
x=21.75
therefore, the tree is 21.75 meters high.
or in fraction form thats 21 & 3/4 meters.
2007-11-29 15:20:25 · answer #4 · answered by ohshizclarissa 4 · 0⤊ 0⤋
divide 4 by 3 - 4/3=1.33(2dp). This means for every meter high an object is, it will produce a 1.33m shadow.
So divide 29 by 1.33 -29/1.33=21.8m.
therefore the tree is 22m high to the nearest m.
2007-11-29 15:27:47 · answer #5 · answered by Anonymous · 0⤊ 0⤋
if the pole is 3 metres high and the shadow 4 then the ratio is 4:3
so divide 29 by 4 which is 7.25 then times that by 3 which is 21.75
im not sure if thats totally correct but it might be :S
2007-11-29 15:16:34 · answer #6 · answered by ? 3 · 0⤊ 1⤋
take the proportion of the shadow of the pole to the pole and apply it to the tree
3 meters /4 meters = .75
29 * .75 = 21.75
the tree is 21.75 meters
2007-11-29 15:19:23 · answer #7 · answered by rob 6 · 1⤊ 0⤋
You use similar triangles.
t = height of tree
3/4 = t/29
t = 3*29/4
t = 21.75 ~ 22 meters
2007-11-29 15:17:24 · answer #8 · answered by T 5 · 0⤊ 1⤋
Ratio problem.
3/4 = x/29
x = 3*29/4
so x = 21.75meters or 22 meters.
2007-11-29 15:18:13 · answer #9 · answered by Neil 7 · 0⤊ 1⤋
I'll admit I tried really hard to figure this out but I had to just give up. but I know it has something to to with a^2+b^2=c^2.
2007-11-29 15:21:01 · answer #10 · answered by Kyle B 1 · 0⤊ 0⤋