What was the meaning behind Howard Arkleys triple fronted

During which period did the artists create works using software such as photoshop, without actually programming

Achair of height 1 m is placed 1 m in front of a plane mirror. a girl is standing 3 m behind the chairas shown. find the minimum length of the plane mirror in order that she can see the whole imageof the chair.a. 0.50 mb. 0.75 mc. 0.80 md. 1.00 m

Sculptures and cave paintings were a development of which period