The chord of contact of the pair the tangents to the circle $x^2+y^2=1$ drawn from any point $2x+y=4$ pass through the point

Question

Let the point be (h,k)

Therefore $$2h+k=4$$ and $$hx+ky=1$$

How do I solve further? Are these lines coincident? If so, why?

Answer 1

The thing you are missing from any external point (X1,Y1) if tangents are dran to the circle X^2 + Y^2= 1 , this equality holds good XX1 + YY1 = 1. Hope this helps