Yes ,Law of reflection is true for concave and convex mirrors too.
In plane mirror , its focus is at infinity while focus of curved mirror is
not at infinity. A ary falls on pole of the curved mirror ,returns in same direction.
For formation of image ,we have certain principle ,for example ,incident
ray parallel to principle axis ,it passes through focus of the mirror.
Here focal point is fixed but in case of plane mirror focus at infinite.
Many principle,you can find in your book.