No. Period. NO. Your problem is that you apparently don't appreciate what acosd means.
Think about what acosd is supposed to do. Start with the cos function, or cosd, since you seem to prefer that version in degrees.
The cosine of any number is a periodic function. It generates a number between -1 and 1, so think about the standard cosine wave, oscillating forever from -1 to 1 and back again. Gets pretty boring, I know.
ezplot(@cosd,[-720,720])
grid on
Now, what does the acosd function do? For ANY number in the interval -1 to 1, it tells you the angle in degrees that corresponds to the given value. It is an inverse cosine function, usually called the arc-cosine, thus acos and acosd.
ezplot(@acosd,[-1,1])
grid on
Now you want to know what acosd(2.7702) is. As a real number. There is NO real number such that when you take the cosine of it, you will get 2.7702. How much time did I just spend explaining that cos(x) NEVER generates greater than 1? So why would you hope that there is some number such that acosd(2.7702) would return a real number?
acosd(1)
ans =
0
acosd(1 + eps)
ans =
0 + 1.2074e-06i
So if we get acosd(1), we get 0, as expected. But increase the input by just a tiny amount, so it is greater than 1, and we suddenly start getting an imaginary part. The real part will always be zero when we do this.
In fact, all of the common trig functions have extensions into the complex plane, so the only solution that works is an imaginary number when the input is greater than 1.
D = acosd(2.7702)
D =
0 + 96.129i
cosd(D)
ans =
2.7702
for inputs less than -1, even by a tiny amount, we will get something like this:
acosd(-1 - eps)
ans =
180 - 1.2074e-06i
essentially a real part of 180 degrees, ALWAYS, but with ALWAYS some imaginary part.
As we see in all this, acosd worked perfectly. But there is no possible way to get it to give you a real number, without an imaginary part. That is just mathematics.
