# Section Formula

This formula is used to find a point which divides a line given between two points $$(x_1,y_1)$$ and $$(x_2,y_2)$$ in 2D or ($$(x_1,y_1,z_1)$$ and $$(x_2,y_2,z_2)$$ in 3D) in a certain ratio. For eg. coordinates for a point that divides the line in l : m ratio are given as:

$$x=\frac{mx_2 + lx_1}{m+l}$$

$$y=\frac{my_2 + ly_1}{m+l}$$

$$z=\frac{mz_2 + lz_1}{m+l}$$

The same formula can be also used to find out points that divide the line externally into any ratio.