7 +b = b +7 is <span>Commutative Property</span>
First solve the triangle:
75° + 75° + x = 180°
150° + x = 180°
x = 180° - 150°
Therefore x = 30°
Then, use the geometrical property of vertically opposite angles.
Therefore. x° = 30°
You can do this by completing the square
x^2 - 14x + y^2 + 8 = 16
(x - 7)^2 - 49 + (y + 4)^2 - 16 = 16
(x - 7)^2 + (y + 4)^2 = 16 + 16 + 49 = 81
so the center is at (7 , -4) and radius = sqrt81 = 9
