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Find the radius of the circle x²+y²-4x-8y-45=0

A√65

B√56

C√34

D√43

Answer:

A. √65

Read Explanation:

x²+y²-2gx-2fy+c=0 2g = -4 ; g=-2 2f= -8 f= -4 c= -45 (h,k)= (-g,-f)=(2,4) radius= √(g²+f²-c)= √(-2)²+(-4)²-(-45))= √4+16+45=√65


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