If the basic angle is 0 how do we know what quadrants to use?

A very good question. One must be very familiar with the shapes of the sine, cosine and tangent graphs and know where the x-intercepts are with respect to the different forms of the abovementioned trigonometry graphs. That is why there are questions that ask for the periods of trigonometric functions. Knowing the period of a trigonometric function immediately allows one to know what the angles are when the function cuts the x-axis.

Let me know if you need further explanation on the question that you have raised.

I see ! I think I understand! thank you very much for your help <3

if the basic angle is 0 how do we know what quadrants to use

Do you know unit circle?
Or
Graph of sin cos wave