find the equation of all the tangents to the curve y = cos (x + y), –2π ≤ x ≤ 2π, that are parallel to the line x + 2y = 0. [2x + 4y – π = 0, 2x + 4y + 3π = 0
For plotting the graph, when we find points to plot on a graph, can we assume any value for x and we will get value of y, or we have to take any particular value of x.