In: Math
Find the local maximum and minimum values and saddle point(s) of the function. If you have three-dimensional graphing software, graph the function with a domain and viewpoint that reveal all the important aspects of the function. (Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.)
1)f(x, y) = 6y cos(x), 0 ≤ x ≤ 2π
2)f(x, y) = y2 − 6y cos(x), −1 ≤ x ≤ 7
3)f(x, y) = 6 sin(x) sin(y), −π < x < π, −π < y < π