Question 473640: The shadow of a flagpole measures 15 feet. At the same day, the shadow of a 2-foot stake measures ¾ foot. How tall is the flagpole?
Answer by oberobic(2304)   (Show Source):
You can put this solution on YOUR website! This problem can be solved with proportions.
We know the triangles are similar because the time of day is the same, so the angle of the sun is the same.
The flagpole and the stake are assumed to be vertical, which makes the shadow at right angles.
So, as flagpole's 15 ft. shadow can be compared to the stake's 3/4 ft shadow, the flagpoles height will be proportional to the 2 ft height of the stake.
15/(3/4) = x/2
Cross multiply
30 = 3/4*x
Multiply both sides by 4 to remove the fraction
120 = 3x
Divide both sides by 3
40 = x
so
x = 40
The flagpole is 40 ft tall.
Done.
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