Final answer:
Renaissance artists used shading to define solid form by employing a technique called chiaroscuro.
Step-by-step explanation:
Leonardo da Vinci and other Renaissance artists were interested in changing and lighting to convey the impression of contour. They defined solid form by shading, or chiaroscuro, which literally means light-dark. Chiaroscuro is an artistic technique developed during the Renaissance that refers to the use of exaggerated light contrasts to create the illusion of volume.