A3cm times 3cm rectangle sits inside a circle with a radius of 4cm what is the area of the shaded region

Plzz on what physical process is responsible for the creation of volcanoes, earthquakes and ocean trenches at the plate margins?

Some gamma ray bursts are hypothesized to come from mergers of neutron stars or black holes. if this hypothesis is correct, what else should we in principle be able to detect from such mergers? a. gravitiational waves b. x-ray bursts c. significant disruption of gas thousands of light-years away in the surrounding galaxy d. an "afterglow" of bright visible light, lasting for weeks

What is the border between layers a through f and layer g called?