Hi
I want check my answers
Are you working in degrees or radians? It looks like you are using radians for (i) and degrees for (ii)! For 4iA, I get a number (assuming radians) close to but not equal to what you have. 4iB, of course, is correct- the cosine must be between -1 and 1 and cannot be larger than 2. For 4iC, it doesn't matter whether you use radians or degrees, of course, but I get an answer nowhere near yours.
4iiA is almost correct. It should be rounded to 47.367 degrees.
You should have gotten "error" again for 4iiB- a cosine cannot be larger than 1. I suspect you took the cosine rather than the arccosine.
For 4iiC, again I got an ansewer nowhere near yours.
For problem 7, I get answers very different from yours.