#"distance between "A(x_1,y_1,z_1) " and " B(x_2,y_2,z_2) " is calculated using :"#
#d=sqrt((x_2-x_1)^2+(y_2-y_1)^2+(z_2-z_1)^2#
#"for "A(-6,3,4)" and "B(-2,2,6)#
#d=sqrt((-2-(-6))^2+(2-3)^2+(6-4)^2)#
#d=sqrt((-2+6)^2+(-1)^2+(2)^2)#
#d=sqrt(16+1+4)#
#d=sqrt(21)#