What is the condition for y=mx+cy = mx + cy=mx+c to be a tangent to the ellipse x2a2+y2b2=1\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1a2x2+b2y2=1?
c2=a2m2+b2c^2 = a^2m^2 + b^2c2=a2m2+b2
c2=a2m2−b2c^2 = a^2m^2 - b^2c2=a2m2−b2
c2=b2m2+a2c^2 = b^2m^2 + a^2c2=b2m2+a2
c2=a2+b2m2c^2 = a^2 + b^2m^2c2=a2+b2m2