Obviously , Its CONVEX mirror as it has +20 radius of curvature and radius of curvature is generally equal to focal length .

Introduction:
The type of mirror can be determined by its radius of curvature. In this case, the radius of curvature of the mirror is 20 cm.

Explanation:
There are two types of mirrors - concave and convex. The type of mirror can be determined based on the radius of curvature.

Concave Mirror:
A concave mirror is also known as a converging mirror or a concave reflector. This type of mirror has a curved surface that bulges inward. The radius of curvature of a concave mirror is positive, and it is equal to the distance between the center of the mirror and the center of curvature.

If the radius of curvature of a mirror is 20 cm, and it is positive, then it is a concave mirror.

Convex Mirror:
A convex mirror is also known as a diverging mirror or a convex reflector. This type of mirror has a curved surface that bulges outward. The radius of curvature of a convex mirror is negative, and it is equal to the distance between the center of the mirror and the center of curvature.

If the radius of curvature of a mirror is -20 cm, then it is a convex mirror.

Conclusion:
In conclusion, the type of mirror can be determined based on the radius of curvature. If the radius of curvature is positive, it is a concave mirror, and if it is negative, it is a convex mirror. In this case, the radius of curvature of the mirror is 20 cm, and it is positive, so it is a concave mirror.