Find locus of point P

Question

If the tangent from point p to circle x²+y²=1 is perpendicular to the tangent from p to be circle x²+y²=3, then locus of p is ?

A circle of radius _

Answer 1

radius = 2

square root of 1^2 + (sqr3)^2 = sqr(1+3) = sqr4 = 2