I don't know what to do. Can someone please help me solve these. I don't even know how to start.

1. Find all solutions in the interval [0, 2pie) of 2cos(x)-square root 3=0

2. Find all solutions in the interval [0, 2pie) of sin(x)=(1/4sin(x))

3. Find all solutions in the interval [0, 2pie) of 3sec^2(x)tan(x)=4tan(x)

4. Find all solutions in the interval [0, 2pie) of sin[x+(pie/4)]+sin[x-(pie/4)]=0