Vector $\(\overline{M}\)$ lies in the xy plane making an angle of θ above the positive x-axis. Vector $\(\overline{N}\)$ is lying in the same plane making an angle Φ below the positive x-axis. Determine their dot product.
Hint: Use one of the following identities-
cos(A + B) = cosAcosB - sinAsinB
cos(A - B) = cosAcosB + sinAsinB