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Suppose you make a model airplane. If you know that the ratio of the length of its wings to the wings of the actual airplane is 1: 100, how can you estimate the length of the real airplane's wing? With this in mind, how might you go about measuring the height of a tall building or a large tree without getting on a ladder and using measuring tape? Explain how you might perform an indirect measurement. Be creative!

1 Answer

5 votes
First to find the length of the wing:
model/real = 1/100
m/r = 1/100*r
m = 1/100*r
m*100 = 1/100*100*r
100*m = r, so just multiply the model wing times 100
Next, to find the height of the building or tree:
A shadow makes a right triangle. We assume the ground is level and that the building or tree is vertical.

You have a ruler or yard stick that you know the height of. it casts a shadow when it is heal vertical and sits on the same ground as the building.

y = height ruler or yard stick
b = height of building or tree
ys = length of rulers shadow
bs = building shadow

so
y:ys as b:bs

36in: 12in as bin:3600in
from now on using inches
36:12 as b:3600

3:1 as b:3600
3/1 as b/3600
3/1 * 3600 = b/3600 * 3600
3/1 * 3600 = b/3600 * 3600
3/1 * 3600 = b
10,800 in = b inches (convert inches to feet)
900 ft= building height in feet.
I really hope this helps! :)
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