Hello, this is my exercise problem, I am confused and have no idea where to start, some help will be much appreciated.

3. a. Let u) = (1, 1, 1). Find the area of the image of the circle C (u), %) under the stereographic projection (x,y,z) = (, 13)- b. Let T be the triangle in R2 with vertices at (0,0), (1,0) and G, ). Find the area of the inverse image of T under the orthogonal projection (ac, y, z) = (53,31)