Factorise [(x + 1) + (x - 1)]^2 - (x - 1)^2 - (x + 1)^2

“exterior angles of triangles. an exterior (or external) angle is the angle between one side of a triangle and the extension of an adjacent side. try this drag the orange dots on any vertex to reshape the triangle.” look to get to the answer i explained what it means and other things i hope it you .