SOLUTION: For some reason I think I was once able to do this problem, but I forgot. Here's how it goes: Two poles 20 feet and 80 feet high are 100 feet apart. What is the height of the po

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Question 159043: For some reason I think I was once able to do this problem, but I forgot. Here's how it goes:
Two poles 20 feet and 80 feet high are 100 feet apart. What is the height of the point of intersection of the lines which run form the top of each pole to the foot of the other pole?
Quick help would be much appreciated.
Thanks, Cameron
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
the easiest solution is semi-graphical

picture the 80 foot pole standing on the origin and going up the y-axis

the 20 foot pole is standing on the x-axis, 100 feet from the origin

y=mx+b

the equation of the line from the top of 80 to the bottom of 20 is y=-.8x+80

the equation of the line from the bottom of 80 to the top of 20 is y=.2x

substituting __ .2x=-.8x+80 __ adding .8x __ x=80

substituting __ y=.2(80) __ y=16