Question For Mathamaticians

[280EZRider]

I am connecting an interior vent pipe to my woodstove. From the stove there will be a pipe straight up about 3 1/2 feet long. It will connect to another pipe that will be at a 45 degree angle continuing up to the ceiling support box.

Measuring from the wall at level to the straight-up pipe, I need to make the connecting end-to-straight-pipe of the 45 pipe 4 inches closer to the wall. But because of the 45 angle, I doubt 4 inches will be correct. Should the 45 pipe be shortened by 8 inches to give me 4 inches less at level?

[cmac2012]

I get 5 and 5/8 inches. That's the math on an equilateral right triangle with each leg 4 inches long. The hypotenuse is the square root of the sum of the squares of each leg. 4 squared + 4 squared = 32, square root is 5.66. Not sure how smoothly that will translate to the real world of stove piping.

[jplinville]

5.625 as well...

[MS Fowler]

I inspect new gas main, and transmission lines. The guys who amaze me are the pipe fitters/welders. Those guys, most with barely a HS education, can intersect 2 -24 inch diameter pipes which are in different planes, and make their cuts within a 1/16 of an inch.

In answer to your question, 5.625 should work.

[cmbdiesel]

Give a man answer and he will work for a day. Give a man an equation and he will work as long as he likes.

A squared + B squared = C squared

works on all right triangles. invaluable for anyone who wishes to build anything.


where c represents the length of the hypotenuse, and a and b represent the lengths of the other two sides.




I would measure the total distances involved (A and B) and do the math with those numbers, rather than trying to tack on the figure calculated for 'extra' length.

[t walgamuth]

I need a picture.

[kerry]

Origami Proof of the Pythagorean Theorem - YouTube

[Kuan]

Plumbing and pipefitting are the only disciplines where the math never works out.

[MS Fowler]

Originally Posted by Kuan

Plumbing and pipefitting are the only disciplines where the math never works out.

Generally true. That is why the gas line pipe fitters/ welders impress me so well. THEIR math works out perfectly, or they are gone. " Close enough" is not good enough for gas line work. It is either right or its replaced. On transmission lines the X-ray EVERY weld, and no arc strikes outside of the groove. As a "farm quality" welder, I find that pretty impressive, too.

[cmac2012]

Welding is a serious talent. The stuff's sorta like alchemy anyway, and then you have a hard time seeing what's going on. I have to put major bright lights on my work cause I hate not having a trace of vision until the arc starts. I have a double 500 watt halogen work light with a tall stand. I can usually get the light on the work so I can faintly see it through the mask w/o the arc.

[Skippy]

Auto darkening masks help a lot with that. I'm still really impressed by a good welder. I can just barely make two pieces of metal stick together.

[MS Fowler]

Auto darkening helmet, and you can teach a chimp to weld. Or so I was told. I know I love mine. Maybe if you weld 8 hours or more a day, they aren't good for your eyes, but for the few hours I weld a year, it sure makes it easy to see what I am doing.

[280EZRider]

5 5/8 inches sounds reasonable, especially after 3 different people come up with the same figure. IŽll give it a try. Thanks

[Botnst]

Put a blower on it. WGAS what the angles are?