what is the most practical way of calculating the angle of two walls which are wider than 90? i want to put u

Question

what is the most practical way of calculating the angle of two walls which are wider than 90?
i want to put up book shelves on that corner.

Answer 1

You'll need :
Paper, pen, ruler, calculator (with trig functions)

I am assuming this is an inside corner and when you are facing it - it is to your front -right, if its to your front-left then reverse wood when making cut. . .. ..

1. Take a piece of paper and lay it flat so that the corner of the paper is directly in the corner where the walls meet ... maybe do this on the floor in that corner.
2. Take a capenter's square and stand it on edge so its short leg is in the corner and the long leg runs across the paper.
3. Trace the line across the paper along the longer leg of the square.

- - - - - - - - - - -The Slope Of The Line - - - - - -

4. Pick any single point along that line, and make a dot that can be easily seen.
5. You now want to measure from that ' Dot ' to each wall.
You should have one wall to your right and one wall directly in front of you. You will have an ' X' and a ' Y ' The wall directly in front of you is the ' Y ' variable, the one to your right is your 'X' variable.

6. Now you should have the measures for your slope, which is in the form of ( Y / x ). Do the math
7. I will call that final answer " m ' this is the " Slope Of that line"
8. Get a Scientific Calculator and you'll use a Trig function called ' Arctangent' Sometimes the Calculator will represent this as " Atan" or " Tan ^-1 ( inverse of Tangent) " Read the book to find out.

9 Calculate Atan ( m ) and this will give you the exact Degree setting for that corner.

[ Example ] :

Let's suppose I drew my line across the paper, and put a dot on it. Now I measure it to the wall in front of me, and the one to my right. I end up with the following numbers.
y = 25 x = 13, that means my slope ' m ' is :

m = 25/13 so now I do the division and I get :
m = 1.92

[ Use Windows Calculator, and enter 1.92 ( click the inverse button) and select " Tan" ]

aTan ( 1.92) = [ 62.38 °]


Remember:
1. Get the slope of the line
2. Use arctangent to get the angle (in degrees) from the slope of the line.


By the way, if your angle is on the left side of you when you are facing it all you have to do is add 90 to the final answer rather than reversing the wood. So the 62.48° is for the angle to my front-right. If the angle were on my front-left it would be ( 62.48 + 90) = 152.48°

A 45° to my front-right, if it were to my front-left it would be :
(45 + 90) = 135°
I know this is correct because the opposite angle of a circle from the 45° is angle 135°

So if your angle is less than 90° it will be to your right, if its greater than 90° it will be to your left.

By the way - this method is more precise than those "Carpenter Protractors"

Answer 2

With all due respect to answer one, who took a decent amount of time and effort in detail, I have a suggestion; a method I use.

I use a tool, that resembles a "Switch Blade" or folding blade knife. It's got a metal blade that has a screw/bolt/nut at one end. The blade is slotted allowing it any angle. It can be tightened to keep the blade/handle AT the chosen angle once applied to any surface. Then I use it against a compass. OR as a pattern to line out the angle for cutting.

Answer 3

Two pieces of cardboard....one piece runs along one wall from the corner....the other piece runs along the other wall from the corner...stick them together with sticky tape or superglue and the two pieces give you the shape of the angle > _|

Answer 4

yea what DIY Doc said,,,,,,you can buy those at home depot or lowes....i forget the name of them though....they'll know in the store