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A circle with centre (4,5) passes through the y-intercept...

A circle with centre (4,5) passes through the y-intercept of the line 5x - 2y + 6 = 0. Find its equation.

A.

x2+y2+8x10y+21=0

B.

x2+y2+8x10y21=0

C.

x2+y28x10y21=0

D.

x2+y28x10y+21=0

Correct answer is D

On the y-intercept, x=0. At this point, y = 5(0) - 2y = -6; y = 3, so the y- intercept has coordinates (0,3).

The equation of the circle is given as (xa)2+(yb)2=r2, where (a,b) is the centre and r is the radius.

The radius of the circle through the y- intercept = (40)2+(53)2=20

The equation of the circle is (x4)2+(y5)2=20; expanding, we have

x2+y2+8x10y+21=0