Using the angle addition formula for cosine, we have:
cos(3π/8 + π/8) = cos(4π/8) = cos(π/2) = 0
Using the angle addition formula for sine, we have:
sin(3π/8 + π/8) = sin(4π/8) = sin(π/2) = 1
Therefore, the expression simplifies to:
0 1 + 1 0 = 0
Using the angle addition formula for cosine, we have:
cos(3π/8 + π/8) = cos(4π/8) = cos(π/2) = 0
Using the angle addition formula for sine, we have:
sin(3π/8 + π/8) = sin(4π/8) = sin(π/2) = 1
Therefore, the expression simplifies to:
0 1 + 1 0 = 0