Two coherent plane waves of identical frequency, polarization, and intensity $I$ interfere at a point where they differ in phase by $60^{\circ}$. What is the resulting intensity?

By a monochromatic wave,we mean

Light waves from two coherent sources arrive at two points on a screen with path difference of $0$ and $\frac{\lambda}{2}$. The ratio of intensities at the points is $(\cos 0^{\circ}=1, \cos \pi=-1)$.

Two coherent monochromatic light beams of intensities $I$ and $4I$ are superimposed. The difference between maximum and minimum possible intensities in the resulting beam is $x I$. The value of $x$ is . . . .

Two identical light waves, propagating in the same direction, have a phase difference $\delta$. After they superpose, the intensity of the resulting wave will be proportional to

Two monochromatic light waves of amplitudes $3 A$ and $2 A$ interfering at a point have a phase difference of $60^{\circ}$. The intensity at that point will be proportional to (in $A^{2}$)