Question

33. The radius of a circle whose centre is (4,0) and
which passes through (7,-4) is-
5 units
6 units
7 units
9 units​

Answer 1

ANSWER

Let (h,k) is a centre of circle , so

(h−7)2+(k−1)2=25

and (h−9)2+(k−5)2=25

Letx2+y2+2gx+2fy+c=0  is  circle .

so, (7,1)  lies  on  circle  so, 

50+14g+2f+c=0     ----(1)

(9,5) lies on circle

106+18g+10f+c=0     ----(2)

and g2+f2−c=25     -----(3)

From (1) & (2),

4g+8f+56=0

g+2f+14=0

From (1), (2), (3), (4),

g=−12  and  f=−1,c=120

so, eqn  of  circle  is

x2+y2−24x−2y+120=0