How does a reflecting telescope work

A reflecting telescope is comprised of two lens namely the primary  mirror which is attached to the tube at one end of the telescope and the secondary mirror, that is kept at the line of sight of the telescope's eyepiece containing a small magnifying lens. This two mirrors, sometimes can also be used as a mixture of convex and concave lens.

According to the law of reflection, a light incident on a plane gets reflected at a same angle.

So, in case of a reflecting telescope, focusing on an object, it allows the light to pass through the tube and strikes on the primary mirror at one end, which gets reflected back to the secondary mirror. This reflected light further gets reflected to the telescope's eyepiece, that enlarges the image and reaches to the eyes.

This is the working principle of a reflecting telescope.