Renaissance painters were influenced by a shading technique known as chiaroscuro, first introduced by which of the following?
a byzantine painter
an islamic painter
a greek painter
a spanish painter

The correct answer is A Greek painter

There are evidences that Greak and Roman artists used the chiaroscuro technique. Reviving ancient Greco-Roman culture the idea of humanism was undoubtedly the engine of this movement and became the very spirit of the Renaissance. It is a deliberate return, which proposed the resurrection of the past, now considered as a source of inspiration and model of civilization.  

answer: this problem has only trivial solutions, with all points on the same line. x=5 or x=7/5.

step-by-step explanation:

there are three triangles, and three unknowns: x, y=length of middle segment, and z=cos(angles marked with red arc).

we need

and law of cosines,

the three equations are

see attached image for solution.

the answer is hope this you.