Question 1061425
{{{m[1]=(2-3)/(1-(-1))=-1/2}}}
{{{m[2]=(-1-2)/(-3-1)=-3/(-4)=3/4}}}
{{{m[3]=(3-(-1))/(-1-(-3))=4/2=2}}}
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Since {{{m[1]*m[3]=(-1/2)(2)=-1}}}, two lines are perpendicular so it is a right triangle.