What kind of mirror, concave, convex or plane, would be best suited for use in a solar cooker? Why?

A concave mirror, also known as a converging mirror would be best suited for use in a solar cooker because it is the only type of mirror that gathers a large amount of sunlight and converges it at a single focal point on the cooker, due to which cooker gets heats up and helps in cooking the food.

Explanation

Parabolic or spherical reflector type solar cookers use a parabolic-shaped reflector (concave mirror) to direct sunlight to a small area in order to generate heat for cooking. The concentrated UV rays reach extremely high temperatures of 260°C (500°F) to 371°C (700°F), which allows them to be used for grilling and frying.