Question #a46b5

1 Answer
Nov 1, 2017

#(x - 67/26)^2+(y - (-17/26))^2= (5/26sqrt370)^2#

Explanation:

Use the standard Cartesian equation of a circle, #(x-h)^2+(y-k)^2=r^2#, and the points, #(0,2),(1,-4),(2,3)#, to write 3 equations:

#(0-h)^2+(2-k)^2=r^2" [1]"#
#(1-h)^2+(-4-k)^2=r^2" [2]"#
#(2-h)^2+(3-k)^2=r^2" [3]"#

Expand the squares:

#h^2+4-4k+k^2=r^2" [1.1]"#
#1-2h+h^2+16+8k+k^2=r^2" [2.1]"#
#4-4h+h^2+9-6k+k^2=r^2" [3.1]"#

Subtract equation [1.1] from equation [2.1]:

#1 - 2h +h^2-h^2+16-4+8k+4k+k^2-k^2 = r^2-r^2#

Combine like terms and mark as equation [4]:

#13-2h+12k = 0" [4]"#

Subtract equation [1.1] from equation [3.1]:

#4-4h+h^2-h^2+9-4-6k+4k+k^2-k^2=r^2-r^2#

Combine like terms and mark as equation [5]:

#9-4h-2k=0" [5]"#

Multiply equation [5] by 6 and add to equation [4]:

#13+54-2h-24h+12k-12k=0

Combine like terms:

#67-26h#

#h = 67/26#

Substitute the value for h into equation [5] and solve for k:

#9-4(67/26)-2k=0#

#2k = 9-4(67/26)#

#k = 9/2-2(67/26)#

#k = -17/26#

Substitute the values of h and k into equation [1] and solve for r:

#(67/26)^2+(2+17/26)^2=r^2#

#r^2 = (67^2+69^2)/26^2#

#r = sqrt9250/26 = 5/26sqrt370#

Substitute the values of h, k, and r into the standard form:

#(x - 67/26)^2+(y - (-17/26))^2= (5/26sqrt370)^2#