Calculating angles

[fredhargis]

What everyone said about needing another value is true, but if the angle of the 2-7' sides is 90° (seems like a reasonable guess), here is what the other angles would be:

angle at the 7'/8' juncture would be 86°
angle opposite the supposed 90° corner would be 85°
angle at the 7'/6.5' juncture would be 99°

It's raining today and I need something to do, and no....I didn't remember the formulas; I had to look them up. Note I rounded the angles to the nearest whole number. Lastly, I'm 69 and could well have screwed it all up, it's been a long time since I did cosines.

Edited to add in the 45° I left off, dang triangles versus 4 sided shapes.

[Jack01]

What everyone said about needing another value is true, but if the angle of the 2-7' sides is 90° (seems like a reasonable guess), here is what the other angles would be:

angle at the 7'/8' juncture would be 86°
angle opposite the supposed 90° corner would be 85°
angle at the 7'/6.5' juncture would be 99°

It's raining today and I need something to do, and no....I didn't remember the formulas; I had to look them up. Note I rounded the angles to the nearest whole number. Lastly, I'm 69 and could well have screwed it all up, it's been a long time since I did cosines.

Edited to add in the 45° I left off, dang triangles versus 4 sided shapes.

Thank you very much.

I was also looking for a formula but could not locate.

[daddo]

Go hither; http://www.mathsisfun.com/quadrilaterals.html

If the lower left corner is 90*, I get 90*, 85*, 104*, 81* going clockwise from 90*.

[Steve N]

I am making a raised flower bed to fit in a certain area.
I cannot make a perfect rectangular box due to shape of the area.  following are the dimensions
I am not smart to figure out the cutting angles , please help me to figure out the angles.

A combination of what has been suggested, unless I just din't understand their answers?

Start at the end where it is most square, and lay down a cross piece that will fit. Mark it as A.

Lay a long member down to see if it will intersect ok at 90*. If it does great, if not you will need more hands to do this easily. Mark it as B.

Check the other long member against the cross piece, how does it work at 90*? Mark it as C.

If both of the long members will work ok at 90* loosely attach them with screws . If not you will need to lay the long members down in the orientation they will be best at, then lay the cross piece over top of the long pieces, and draw a line where they meet. You will effectively be drawing your angle. Carefully cut that angle, once done you can again lightly screw the pieces together. It is while trying to keep the boards straight, and set the crossing piece that you may be helped with other hands. Kids are pretty good for this kind of thing, they love to help
If no help is available, lightly screw the cross piece into the long members just enough to hold them in place while you mark the angle.

Once you have 3 sides, just lay the second crossing piece, part D across, and mark your lines. make those last cuts, you may need to unscrew what you have lightly screwed if you want to use a chop saw. Just lift the end up, and put it on a riser if using a circular, reciprocating, hand saw or other to cut.

Screw it all together. From another recent thread, you can strengthen the hold quite a bit doing this before your final screws go in.

[Paul-in-Plymouth]

I like the cross-grain anchor in Steve N.'s photo.  Nice idea.

[Paul-in-Plymouth]

I found responses to this posting really interesting from the standpoint of the variety of approaches to the OP’s problem.  

Some said one additional piece of information is needed to completely specify the problem.  

Some made a reasonable assumption about that additional piece of information and solved the problem based on that assumption, either by trigonometry (compass and graph paper would work too) or using a black-box program from the Web.  

Some said redesign it to be square or rectangular and avoid the angles.  

Some said don’t bother to figure the angles at all, just build it and fit the angles as you go along.  

Some included practical details for “just building it.” 

Any of these approaches could be made to work, and I trust the OP found one to his liking.  I like to see the different ways different people approach a problem.   It’s part of the fun of this Forum.

[Steve N]

Different strokes for different folks. Plus there is always more than one way to skin a cat. I like to know as many as I can cram into my head, because some depend on tool availability, and circumstance.