15. In this exercise, we determine the equation of a plane tangent to the surface defined by f(z,y) = \\/x2 + y?2 at the point (3,4, 5). o, Find a parameterization for the x = 3 trace of f. What is a direction vector for the line tangent to this trace at the point (3,4, 5)? Find a parameterization for the y = 4 trace of f. What is a direction vector for the line tangent to this trace at the point (3,4, 5)? The direction vectors in parts (a) and (b) form a plane containing the point (3,4,5). What is a normal vector for this plane? Use your work in parts (a), (b), and (c) to determine an equation for the tangent plane. Then, use appropriate technology to draw the graph of f and the plane you determined on the same set of axes. What do you observe? (We will discuss tangent planes in more detail in Chapter 10.)