Matrix plays an important role in computer science. It is useful in various computer programs, in projecting a three-dimensional image onto a two-dimensional plane.
With matrix multiplication it is easy to project a 3D object to 2D plane, see https://en.wikipedia.org/wiki/3D_projection, which is a basic operation in computer graphics.
Probably the formula of least square projection of a vector unto a matrix is a hint. Please check it on Khan academic. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=2ahUKEwjA1tCt67fpAhWfD2MBHdMgBLcQFjACegQIDBAF&url=https%3A%2F%2Fwww.khanacademy.org%2Fmath%2Flinear-algebra%2Falternate-bases%2Forthogonal-projections%2Fv%2Flin-alg-a-projection-onto-a-subspace-is-a-linear-transforma&usg=AOvVaw3Nmqk8G0nMPhS1WzGeEO83