A spherical mirror is to be used to form an image, two times as tall as an object, on a screen positioned 5.8 m from the mirror. (a) Describe the type of mirror required. The mirror is a concave mirror. Correct: Your answer is correct. ******and it has a focal length of _____ m. (b) Where should the mirror be positioned relative to the object? The object should be _____ m in front of the mirror.