(a) A far-sighted patient is prescribed contact lenses of focusing power P = +2.75 D to correct the location of her near point. Where was her near point before correction? (b) Suppose the patient of part (a) decides she prefers glasses to contact lenses. If the lenses of the glasses are 3 cm from her eye, what should the power of these lenses be? (c) Another patient (near-sighted) is prescribed contact lenses of power P =-1.3 D to correct his long-distance vision. What was his far point before correction?