Let the centre of the circle \( x^2+y^2+2gx+2fy+25=0 \) be in the first quadrant and lie on the line \( 2x-y=4 \). Let the area of an equilateral triangle inscribed in the circle be \( 27\sqrt{3} \). Then the square of the length of the chord of the circle on the line \( x=1 \) is ______.
