`(1)` Coordinatesa point `P` which divides line joining `A(x_1, y_1 , z_1)` and `(x_2, y_2, z_2)` in the ratio `m: n` internally is given by
`quadquadquadquadquadquad( (mx_2+nx_1)/(m+n) ,(my_2+ny_1)/(m+n) ,(mz_2+nz_1) /(m+n) )`.
`(2)` Coordinates of a point `P` which divides line joining `A(x_1 ,y_1 , z_1)` and `B (x_2, y_2, z_2)` in the ratio `m: n` externally is given by
` quadquadquadquadquadquad( (mx_2 -nx_1) /(m-n) ,(my_2-ny_1)/(m-n) , (mz_2-nz_1)/(m-n) )`.
`(3)` Coordinates of mid-point of line joining `A (x_1, y_1, z_1)` and `B (x_2, y_2, z_2)` is
` quadquadquadquadquadquad( (x_1 +x_2)/(2) , (y_1 +y_2) /(2) , (z_1+z_2) /(2) )`.
`(1)` Coordinatesa point `P` which divides line joining `A(x_1, y_1 , z_1)` and `(x_2, y_2, z_2)` in the ratio `m: n` internally is given by
`quadquadquadquadquadquad( (mx_2+nx_1)/(m+n) ,(my_2+ny_1)/(m+n) ,(mz_2+nz_1) /(m+n) )`.
`(2)` Coordinates of a point `P` which divides line joining `A(x_1 ,y_1 , z_1)` and `B (x_2, y_2, z_2)` in the ratio `m: n` externally is given by
` quadquadquadquadquadquad( (mx_2 -nx_1) /(m-n) ,(my_2-ny_1)/(m-n) , (mz_2-nz_1)/(m-n) )`.
`(3)` Coordinates of mid-point of line joining `A (x_1, y_1, z_1)` and `B (x_2, y_2, z_2)` is
` quadquadquadquadquadquad( (x_1 +x_2)/(2) , (y_1 +y_2) /(2) , (z_1+z_2) /(2) )`.