For this case we must solve the following equation:

So we have to:
Applying square root to both sides of the equation:

Thus, we have two roots:

Answer:

If tan α = 0
α = tan^(-1) 0
α = k π , k ∈ Z ( any integer ), π = 180°
0 · 180° = 0
1 · 180° = 180°
2 · 180° = 360°
3 · 180° = 540°
Answer:
Angles are: 0°, 180°, 360°, 540°.
Didn't you mean "Find the possible value or values of z? y is not at all present in this equation.
z^2 - 4z + 4 = 0 can be factored into (z-2)(z-2). Thus, the given equation has two equal, real solutions: z=2 and z=-2.
Since we know the side length of the square (6), we can calculate its diagonal using pythagoras.
diag d = √(6²+6²) = 6√2 in
The diagonal is also the diameter of the circle! So the radius of the circle is half of that:
radius r = d/2 = 3√2 in
The area of the circle is πr² = π(3√2)² = 18π in²