Докажите равенство (x-z)^2+(y-z)^2+(y-t)^2=(x-t)^2
(x-z)^2+(y-z)^2+(y-t)^2=(x-t)^2 х²-2хz+z²+y²-2yz+z²+y²-2yt+t²=x²-2xt+t²