What type of mirror should be used:(a) as a shaving mirror?(b) as a shop security mirror?

(a) A concave mirror should be used as a shaving mirror.

Explanation

To shave the beard properly and safely, we need to see an enlarged image of our face, that's why we should use a concave mirror because when the face is placed close to a concave mirror (within the focus of the mirror) it produces a virtual, erect and magnified image of the face.

(b) A convex mirror should be used as a shop security mirror.

Explanation

For vigilance purposes in the shop, a convex mirror is used because it gives a wider field of view and always forms virtual, erect, and small-sized images of a large number of objects at the same time.