If $$\theta$$ + $$\phi$$ = $$\pi$$/4, then (1 + tan $$\theta$$) (1 + tan $$\phi$$) is equal to

If $$\sin \theta + \cos \theta = 0$$ and $$0 < \theta < \pi $$, then $$\theta$$ =

The value of cos 15$$^\circ$$ $$-$$ sin 15$$^\circ$$ is

The expression $$\cos ^2 \phi+\cos ^2(\theta+\phi)-2 \cos \theta \cos \phi \cos (\theta+\phi)$$ is