The equation x2 + y2 = 4 of circle C makes two tangent lines of circle C through M (2,4) The equation x2 + y2 = 4 of circle C makes two tangent lines of circle C through M (2,4) The tangent point is a B The line AB just passes through the right vertex and the upper vertex of the ellipse T: x2 / A2 + Y2 / B2 = 1 Find t

The equation x2 + y2 = 4 of circle C makes two tangent lines of circle C through M (2,4) The equation x2 + y2 = 4 of circle C makes two tangent lines of circle C through M (2,4) The tangent point is a B The line AB just passes through the right vertex and the upper vertex of the ellipse T: x2 / A2 + Y2 / B2 = 1 Find t

Point (x ', y') to m (2,4) is equal to let a tangent length be 4 (2-x ') ^ 2 + (4-y') ^ 2 = 16x ^ 2 + y ^ 2-4x-8y + 8 = 0 (x2 + y2 = 4) x '= 2-2y' brought into x2 + Y2 = 4 to get X '= - 6 / 5 y' = 8 / 5 straight line AB equation is y = - 1 / 2 (X-2) let x = 0 y = 1 Let y = 0 x = 2 so B = 1A = 2 ellipse T: x2 / 2 ^ 2 + y2 = 1