Find the length of chord of contact of the tangents drawn from point (x1,y1) to the parabola y2=4ax
Open in App
Solution
Let tangent at P(t1)&Q(t2) meet at (x1,y1) ∴at1t2=x1 & a(t1+t2)=y1 ∵PQ=√(at21−at22)2+(2a(t1−t2))2 =a√((t1+t2)2−4t1t2)((t1+t2)2+4)=√(y12−4ax1)(y12+4a2)a2