Let the centre of the circle x^2+y^2+2 g x+2 f y+25=0 be in the first quadrant and lie on the line 2 x-y=4. Let the area of an equilateral triangle…

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