Answer :
Spherical mirrors were discovered in the 15th centuries which were in the shape of a curved glass piece. Those days these type of mirrors were so expensive which led them to be luxurious. Many discoveries were done in the part of mirrors. Atlast it resulted in the mirrors like concave mirrors etc. Such as Spherical mirrors were a great discovery which still exists with a vast use. The people used mirrors made of polished stone etc. in the ancient times. The silvered-glasses was found by Justus Von in 1885. His invention made the mirrors affordable and large scale factories for mirrors were established.