1) First, we will simplify the left side of the equation:
sinx cos3x - 1 = sinx - cos3x
sinx cos3x = sinx + cos3x - 1
sinx * (3-4sin^2(x)) = sinx + cos3x - 1
3sinx - 4sin^3(x) = sinx + 4cosx - 1

This cannot be simplified further without the exact values of sinx and cosx.

2) To find the square root of sinx=0, we need to find the values of x that make sinx equal to 0. Since sinx=0 when x is a multiple of π, the square root of sinx=0 is sinx=0 for all x such that x=n*π, where n is an integer.