If 7 l 2 − 9 m 2 + 8 l + 1 = 0 , the line l x + m y + 1 = 0 is tangent to a circle with centre ( 4 , 0 ) and radius 3. If 16 l 2 + 9 m 2 = 24 l m + 6 l + 8 m + 1 and S = 0 is the circle having l x + m

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If 7 l 2 − 9 m 2 + 8 l + 1 = 0 , the line l x + m y + 1 = 0 is tangent to a circle with centre ( 4 , 0 ) and radius 3. If 16 l 2 + 9 m 2 = 24 l m + 6 l + 8 m + 1 and S = 0 is the circle having l x + m y + 1 = 0 as a tangent, the director circle of S = 0 is

TestHub · Accepted Answer

From the printed condition, (3l+4m+1)^2=25(l^2+m^2). The circle has centre (3,4) and radius 5. Its director circle is (x-3)^2+(y-4)^2=50, equivalently x^2+y^2-6x-8y=25. Answer C.

Mathematics - Circle Question with Solution | TestHub

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