<P> The image location and size can also be found by graphical ray tracing, as illustrated in the figures above . A ray drawn from the top of the object to the surface vertex (where the optical axis meets the mirror) will form an angle with that axis . The reflected ray has the same angle to the axis, but is below it (See Specular reflection). </P> <P> A second ray can be drawn from the top of the object passing through the focal point and reflecting off the mirror at a point somewhere below the optical axis . Such a ray will be reflected from the mirror as a ray parallel to the optical axis . The point at which the two rays described above meet is the image point corresponding to the top of the object . Its distance from the axis defines the height of the image, and its location along the axis is the image location . The mirror equation and magnification equation can be derived geometrically by considering these two rays . </P> <P> The mathematical treatment is done under the paraxial approximation, meaning that under the first approximation a spherical mirror is a parabolic reflector . The ray matrix of a spherical mirror is shown here for the concave reflecting surface of a spherical mirror . The C (\ displaystyle C) element of the matrix is − 1 f (\ displaystyle - (\ frac (1) (f))), where f (\ displaystyle f) is the focal point of the optical device . </P> <P> Boxes 1 and 3 feature summing the angles of a triangle and comparing to π radians (or 180 °). Box 2 shows the Maclaurin series of arccos ⁡ (− r R) (\ displaystyle \ arccos \ left (- (\ frac (r) (R)) \ right)) up to order 1 . The derivations of the ray matrices of a convex spherical mirror and a thin lens are very similar . </P>

How are images in concave mirrors like images in convex mirrors how are they different