Questions
If the chords of contact of the tangents from a point on the circle to the circle touch the circle then the roots of the equation are
detailed solution
Correct option is B
Let P(x1, y1) be a point on x2+y2=a2. Then, x12+y12=a2 …(i)Let QR be the chord of contact of tangents drawn from P (x1 , y1) to the circle x2 + y2 = b2. Then, the equation QR is xx1+yy1=b2 …(ii)This touches the circle x2+y2=c2∴ 0x1+0y1−b2x12+y12=c⇒b2=ac [Using: (i)]Let D be the discriminant of ax2 + 2bx + c = 0. Then, D=4b2−ac=0 ∵b2=acHence, the roots of the given equal are real and equal.Talk to our academic expert!
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