D-o d-i doesnt matter. So the focus will be at 0 05 and the directrix is the line y -05. F R cos.
Solving the equation above for focal length will be 127X10166096 212mm.
Then the distance of the foci from the centre will be equal to a2-b2. F R cos. Yx22 So we have. In the sign convention used in optical design a concave mirror has negative radius of curvature so.