# mathematical and calculation formula for angles

1. ## mathematical and calculation formula for angles

i have a problem at present. i have 2 problems.
the 1st problem is i do not know the mathematical calculation or theory to work out what i need to know and therefore i have no idea how to write a formula for excel either.

i will describe my issues and hope someone may be able to help.

i have a block. length is 100mm and width is 50mm
i have measured the block in all 4 corners to find the thickness of the block
top left corner is 4.75mm
top right corner is 4.77mm
bottom left corner is 3.86mm
bottom right corner is 3.89mm

i would like to try and find out the angle differences accross the block
so i would like to know what the angle is between the top left hand corner and the bottom left hand corner, the angle difference between the top right hand corner and the bottom right hand corner and i would also like to know what the angle difference is across the whole length of the block.

if someone could help me with this it would be fantastic

2. ## Re: mathematical and calculation formula for angles

the 1st problem is i do not know the mathematical calculation or theory to work out what i need to know and therefore i have no idea how to write a formula for excel either.
I can appreciate this problem. Since I find that I must first understand the math before I can hope to program the spreadsheet, I will first suggest some math/geometry/trigonometry tutorials:

http://www.purplemath.com/modules/rghtprob.htm Perhaps the most important take away from this one is that the best first step in solving these problems will probably be a simple sketch of the problem. A quick sketch, labeling the knowns and unkowns will be useful in identifying the trigonometric/geometric relationships between the knowns and unkowns. If we assume that the sides of your box are rectangles, this might also include adding diagonals to make right triangles and so on.

Since I expect basic trig will come into play, here's a quick look at the basic trig ratios: http://www.math-only-math.com/basic-...ic-ratios.html Each of these has an excel function associated with it http://office.microsoft.com/en-us/ex...944.aspx?CTT=1 Recognize that Excel (like almost all programming languages) deals with angles in radians, so you may need to dust off your recollection of the relationship between degrees and radians (and how to use the degrees() and radians() functions).

Should be a fun (because I am just evil enough to think that math is fun) (devil smiley here) exercise and an opportunity to recall the math/geometry/trig you learned way back in high school.

3. ## Re: mathematical and calculation formula for angles

Originally Posted by maestro_uk
i have a block. length is 100mm and width is 50mm
i have measured the block in all 4 corners to find the thickness of the block
top left corner is 4.75mm
top right corner is 4.77mm
bottom left corner is 3.86mm
bottom right corner is 3.89mm

i would like to try and find out the angle differences accross the block
so i would like to know what the angle is between the top left hand corner and the bottom left hand corner, the angle difference between the top right hand corner and the bottom right hand corner and i would also like to know what the angle difference is across the whole length of the block.

4. ## Re: mathematical and calculation formula for angles

 A B C D 1 Height 100 2 Width 50 3 Corner Thicknesses 4.75 4.77 4 3.86 3.89 5 Angles [deg] 6 TL to TR 0.023 B6: =DEGREES(ATAN(C3-B3)/B\$2) 7 BL to BR 0.034 B7: =DEGREES(ATAN(C4-B4)/B\$2) 8 9 TL to BL -0.417 B9: =DEGREES(ATAN(B4-B3)/B\$1) 10 TR to BR -0.413 B10: =DEGREES(ATAN(C4-C3)/B\$1) 11 12 TL to BR -0.364 B12: =DEGREES(ATAN(C4-B3)/SQRT(B2^2+B1^2))

Note that the top of the block is not flat.

5. ## Re: mathematical and calculation formula for angles

Only thing to add to shg's post above is that the angle he gave you across the diagonal from BL to TR will be smaller than the angle across the diagonal if you took it from TL to BR due to the greater difference between the hieghts. His formula is still right of course you just need to decide which difference in Heights you require - the greatest difference for the greatest angle or the smallest difference for the smallest angle

6. ## Re: mathematical and calculation formula for angles

thanks for all the replies.

i will take a look at some of the maths links as i do need to refresh my maths

i will also look at shg's answer to see if i can reproduce this with some answers someone has given me now on paper also.

but overall a big thank you to everyone who has replied in this forum.

once again a big thank you

7. ## Re: mathematical and calculation formula for angles

You're welcome.

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