`TXD:cos^2 x ne 0`
`G=(\sqrt{[(1+sin x)^2]/[(1-sin x)(1+sin x)]}-\sqrt{[(1-sin x)^2]/[(1+sin x)(1-sin x)]})^2`
`G=([|1+sin x|]/\sqrt{1-sin^2 x}-[|1-sin x|]/\sqrt{1-sin^2 x})^2`
`G=([1+sin x-1+sin x]/[\sqrt{cos^2 x}])^2` `(1+sin x >= 0;1-sin x >= 0)`
`G=([2 sin x]/[|cos x|])^2`
`G=[4sin^2 x]/[cos^2 x]`
\(G=\dfrac{1+sinx}{1-sinx}+\dfrac{1-sinx}{1+sinx}-2\cdot\sqrt{\dfrac{1+sinx}{1-sinx}\cdot\dfrac{1-sinx}{1+sinx}}\)
\(=\dfrac{\left(1+sinx\right)^2+\left(1-sinx\right)^2}{1-sin^2x}-2\)
\(=\dfrac{1+2\cdot sinx+sin^2x+1-2\cdot sinx+sin^2x}{cos^2x}-2\)
\(=\dfrac{2+2\cdot sin^2x-2cos^2x}{cos^2x}\)
\(=\dfrac{2+2sin^2x-2\left(1-sin^2x\right)}{cos^2x}=\dfrac{4sin^2x}{cos^2x}\)
