Technically correct, but since range is measured from the base of the ship (not the center), the area you can actually hit is a quarter circle with a "flat space" in the middle that is exactly the width of the ship base. See the illustration below (from Vassal) to see what I'm talking about.
A firing arc is also not 45 degrees, because the the "aim-lines" (for lack of a better word) are not half-diagonals of a square, they're half diagonals of a rectangle that's smaller in its width than its length. It's somewhere between 41-43 degrees depending on your inclusion of the width of the lines themselves or not.
4 X-Wing 6 TIE Fighter
2 Y-Wing 2 Advanced TIE
4 A-Wing 4 TIE Interceptor
2 YT-1300 2 Firespray-31