What are the relative maximum/minimum and stationary points of f(x)=sinx+cosx where 0<=x<= pi

I believe stationary points are values where the derivative is zero, right?

Find the derivative, set it to zero or undefined to find critical points, then make a sign chart to find the max and mins:

f'(x) = cos(x) - sin(x)
--> there are NO values for which f'(x) is undefined, so just set this to zero

cos(x) - sin(x) = 0
-->

cos(x) = sin(x)

Find points where the sine and cosine have the SAME value...go to your unit circle and find the points where the x and y value are the same...well that's easy, it's just at the 45° (π/4) angles:

So there are four candidates:

π/4
π - π/4 = 3π/4
π + π/4 = 5π/4
2π - π/4 = 7π/4

However, the last two AREN'T in our rang