Draw the graph of `y = sin x + cos x, x in [0, 2pi].`

Explanation

We have `y = f(x) = sin x + cos x, x in [0, 2pi]`
To draw the graph, we need to decide the points to be plotted.
f(x) = sin x + cos x
`= sqrt(2)((1)/(sqrt(2))sin x + (1)/(sqrt(2))cos x)`
`= sqrt(2)sin (x + (pi)/(4))`
`f(0) = 1, f((pi)/(4)) = sqrt(2), f((pi)/(2)) = 1`
`f((3pi)/(4)) = 0, f(pi) = -1, f((5pi)/(4)) = -sqrt(2)`,
`f((3pi)/(2)) = -1, f((7pi)/(4)) = 0, f(2pi) = 1`,
Plotting these points and joining them, we get the graph as shown in the gfollowing figure.