Based off my former knowledge your answers do indeed look correct
Well, if you cut a circle in 4 parts, each part will equal 90 degrees. But if you cut one of those parts in half again it will cut the degrees in half. Thus, making the degrees of that half a part 45. Your answer should be 45 degrees.
The answer is f−1(x)=5x2−z2−1
All you have is one point on the line. There are an infinite number of different lines
that can go through it. You can't find the equation of any particular line without
some more information. You need another point, or the slope of the line, or one
of the intercepts of the line.