deminki yazdığım referans cevabı kullanarak ta.
$-cos(x+60)=cos(x+60+180)=cos2x$ yazabilirim
$2x_1$ : $x_1+240+2\pi.k$
$\longrightarrow$ $\boxed{\boxed{x_1:240+2\pi.k}}$
$2x_2$ : $-x_2-240+2\pi.k$
$\longrightarrow$ $3x_2:120+2\pi.k$
$\longrightarrow$ $\boxed{\boxed{x_2:40+\dfrac{2\pi.k}{3}}}$