Given, equation of circles x2+y2=16 And (x−9)2+y2=16 C1‌=(0,0),r1=4 C2‌=(9,0),r2=4 ∴‌‌C1C2‌=√(9−0)2+(0−0)2 ‌=√(9)2=9 And r1+r2=4+4=8 Since C1C2>r1+r2 Circles are separate to each other, any tangent to circle (i) with slope ( m ) is ‌y=mx±r√1+m2 ⇒y=mx+4√1+m2 ⇒mx−y±4√1+m2=0 Equation (iii) to be tangent to circle (ii) ∴‌|‌