Consider the following lines C1 and C2 : C1: y/3=x/3+1 C2: y/3=-x/3+1 Let C3 be the straight line which is perpendicular to C2C2 and whose y-intercept is 4. Define S1to be the set of points of...

Consider the following lines C1 and C2 :

C1: y/3=x/3+1

C2: y/3=-x/3+1

Let C3 be the straight line which is perpendicular to C2C2 and whose y-intercept is 4.
Define

• S1to be the set of points of intersection of C1 and C2


• S2 to be the set of points of intersection of C1 and C3


• S3 to be the set of all the points of intersection of "C1 and C2" or "C2 and C3" or "C1 and C3".

What is the cardinality of S1?S2?