COS not working and strange results

Hi,

I'm doing a bigger trigonometric calculation in excel and my answers are very strange in some cells.
I'm double checking them with my calculator and they do answers differently...

Let me try to sum it up,
Triangle: a=7, b=6, c=8, A=75,52', B=46,57', C=57,91'

I want to calculate the "a" on each side of the center line of angle C.
This gives me a easy calculation to give me a right triangle. C1=180-(90+75,52) = 14,48' & C2=180-(90+46,57) = 43,43'. checksum = 14,48+43,43 = C57,91
then to do pytagoras to calculate the new "a", i need to find the height of the new b/c: b = COS(14,48)*6 = 5,80 & c = COS(43,43)*8 = 5,80.
BUT in excel this gives me two different results on the same calculation.

=COS(DEGREES(H2))*B2 (gives me the correct result)
=COS(DEGREES(J2))*C2 (gives me wrong result)

excel file is attached pyta.xlsx

What am i doing wrong?

If i should use RADIANS(), why is then the first answer correct? the formulas are the same, just the values that are changed.
Doing this on the calculator on my desk gives the correct result.

Originally the triangle is not straight, but after i broke it up and used the new angles that makes angle A/B=90', then i have a straight triangle.

Check out the file attached in the original file. The calculations in cell M2 and N2 should give the same result, that is 5,956934 as i get on my calculator in both cases using the same formulas.

This is somehow confusing.

This is where the good part comes, i drawed the triangle in Autocad, and measured the angles and lengths, and they all match out. All the values are taken from a example of the equations. The calculations do match everywhere except when i move on to find the splitted parts of the triangle. The difference in values from excel and calculator i found being the difference in number of numbers after the comma.
As you see in my excel sheet, i have checksums for selveral calculations to make sure everything is correct. At the end the check in Q2 should be equal to A2.

The arccos calculation is also strange, yes. but if you sum the arccos with the 2 other angles, they do not result in 180'. therefore there is something wrong here to. I drawed this in autocad too, and measured the angle to 14,5, when drawing a straight line from angle C in 0'(orthocenter). this gives A=75,5, B=90, C=14,5. Only value to change when doing so is angle B and C, no change in lengths of the legs.

I must be honest to say that i have never worked with radians, and i somehow lose control if to start using radians instead of degrees. Anyhow, based on your conclution, this means excel does it's calculations with consistency. Due to all my answers are correct, and cross checked on the calculator except for the N2 calculation. And later on the O2:Q2 is wrong, but thats on my end for now!

I would guess the fault is on my side, since excel just handles it's input and retrieves an answer, but two formulas with the "same" input retrieves different result, this is to me odd.