The problem is: The temperature (in degrees Celsius) of a metal plate, located in the xy -plane, at any point (x, y ) is given by the function of two variables T(x, y ) = x sin y + y2 sin x. (a) Find the rate of change in temperature in the direction of the positive x-axis at the point (π, π). (b) Find the rate of change in temperature in the direction of the positive y -axis at the point (π, π). I am thinking that you would have to find the gradient vector of T(x,y), then plug the point (π, π). But the phrase "direction of the positive x-axis/y-axis at the point" is throwing me off. Does that mean you would have to find the directional derivative instead? So find the gradient vector then multiply it by a unit vector, but what is the unit vector? Thanks.