12. Consider the solid to be shown below, defined in the first octant and bounded by the surfaces x2 + z = 1,x2 + y' = 1, x = 0, y = 0,z =0 Z The projection of the previous solid on the YZ plane is composed of two regions R1 and R2. Such regions are determined by the points (y, z) such that: A) R1 : Oyl AOS= Sy y R2 : 0