The general form of the equation of a circle is 7x2 + 7y2 − 28x + 42y − 35 = 0. the equation of this circle in standard form is . the center of the circle is at the point , and its radius is units.

7 x² + 7 y² - 28 x + 42 y - 35 = 0  /: 7
x² + y² - 4 x + 6 y - 5 = 0
( x² - 4 x + 4 ) + ( y² + 6 y + 9 ) - 4  - 9 - 5 = 0
The equation in the standard form is:
( x - 2 )² + ( y + 3 )² = 18
The center is at the point ( 2, - 3 ).
Its radius is: √18 = 3√2 units.

Answer d; a supplementary angle = 180°, so if that angle = 150°, y would = 30°.