SOLUTION: A large pipe is placed next to a wall and a 1 ft high block is placed 5 ft from the wall to keep the pipe in place as show in the figure. What is the radius of the pipe ? The answe

Question 349269: A large pipe is placed next to a wall and a 1 ft high block is placed 5 ft from the wall to keep the pipe in place as show in the figure. What is the radius of the pipe ? The answer in the book says 6-square root 10, but I'm not sure how they got that answer. I have a link to the image from my textbook.
http://img237.imageshack.us/img237/2158/dsc00343ts.jpg
Found 2 solutions by Alan3354, Fombitz:
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
Extend a line from the top of the block to the vertical line thru the center of the pipe.
You get a right triangle with r as the hypotenuse.

If you solve that you'll get 6 � sqrt(10)
6 - sqrt(10) is the answer.
6 + sqrt(10) puts the block on the other side of the pipe, between the pipe and the wall.
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btw, that's not a "large" pipe, less than 3 ft OD.

Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!

You can find the triangle with the green leg since the triangle is a right triangle with the other leg and hypotenuse of .

.
.

.
.
Substituting,

Complete the square,

Since , then must be less than .
So,

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