In any given coordinates #(x,y)#, the sign of abscissa i.e, #x# coordinate and the sign of ordinate i.e. #y# coordinate, both together decide the quadrant in which the pont lies.
If both #x# and #y# are positive, the point lies in first quadrant;
if #x# coordinate is negative and #y# coordinate is positive, the point lies in second quadrant;
if both #x# and #y# are negative, the point lies in third quadrant; and
if #x# coordinate is positive and #y# coordinate is negative, the point lies in fourth quadrant.
Graphically it can be shown as in image below.
)
In #(-1,-2)# as both #x# and #y# are negative, the point lies in third quadrant.
