SOLUTION: the equations of two circles are x^2 + y^2 - 2x + 4y - 20 = 0 and x^2 + y^2 + 4x - 6y = 0 (a) find the distance between the centres of these circles (b) find the radii of the two

Question 1124998: the equations of two circles are x^2 + y^2 - 2x + 4y - 20 = 0 and x^2 + y^2 + 4x - 6y = 0
(a) find the distance between the centres of these circles
(b) find the radii of the two circles
(c) determine relationship between the two circle
Answer by rothauserc(4718) (Show Source): You can put this solution on YOUR website!
x^2 + y^2 - 2x + 4y - 20 = 0
:
x^2-2x+1 +y^2+4y+4 = 20+5
:
(x-1)^2 +(y+2)^2 = 25
:
center of this circle is (1,-2) and radius is 5
:
x^2 + y^2 + 4x - 6y = 0
:
x^2+4x+4 +y^2-6y+9 = 13
:
(x+2)^2 +(y-3)^2 = 13
:
center of this circle is (-2,3) and radius is square root(13) = 3.6056
:
a) distance = square root( (-2-1)^2 + (3-(-2))^2 ) = 5.831
:
b) radii are 5 and 3.6056
:
c) the given circles intersect at two points
:

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