Taking the right focus of the hyperbola x square / 9-y square / 16 = 1 as the center of the circle, and the equation of the circle tangent to the two asymptotes is

Taking the right focus of the hyperbola x square / 9-y square / 16 = 1 as the center of the circle, and the equation of the circle tangent to the two asymptotes is


a²=9
b²=16
c²=9+16=25
Right focus (5,0)
Asymptote y = (± B / a) x = (± 4 / 3) x
That is 4x ± 3Y = 0
Radius is the distance from right focus to asymptote = | 20 ± 0 | / √ (4 & sup2; + 3 & sup2;) = 4
So (X-5) & sup2; + Y & sup2; = 16



Given that the real axis of hyperbola is 4 and the root sign is 5, the focus is on the Y axis and passes through point a (2, - 5), then the standard equation of hyperbola is?


Let the equation be y ^ 2 / A ^ 2-x ^ 2 / b ^ 2 = 1
A = (4 radical 5) / 2 = 2 radical 5
That is y ^ 2 / 20-x ^ 2 / b ^ 2 = 1
Substituting a (2, - 5): 25 / 20-4 / b ^ 2 = 1
B ^ 2 = 16
The equation is y ^ 2 / 20-x ^ 2 / 16 = 1