Mathematics - Properties of Triangle Question with Solution | TestHub

Put x=s-a,y=s-b,z=s-c. Then s=x+y+z, ${\Delta }^2$=sxyz and r_i=$\Delta$/x_i. The sum of pairwise products is ${\Delta }^2$ (x+y+z)/(xyz) = ${\Delta }^2$·s/(xyz)=$s^2$. As r=$\Delta$/s, $s^2$=${\Delta }^2$/$r^2$.