Given circle x2+y2=50 ...(i) and a line x+7=0 ...(ii) Point of intersection of Eqs. (i) and (ii) is x=−7, y=±1 ∴(−7,1) and (−7,−1) are points of contact of Eqs. (i) and (ii), for circlex2+y2=r2 Equation of tangent at (x1,y1) is xx1+yy1=r2 ∴ Equation of tangent of Eq. (i) at (−7,1) and (−7,−1) are −7x+y=50 or 7x−y+50=0 and−7x−y=50 or 7x+y+50=0