A relation is (also) a function if every input x is mapped to a unique output y.
In terms of graphical representation, this implies that a graph represents a function if there doesn't exist a vertical line that intersects the graph more than once. So:
- The first graph is exactly a vertical line, so it's not a function.
- The second graph represents the function y=x, so it's a function: you can see that every possible vertical line crosses the graph only once.
- The third graph is not a function, because you can draw vertical lines that cross the graph twice.
- Similarly, in the fourth graph you can draw vertical lines that cross the graph twice
- The fifth graph is a function, because every vertical line crosses the graph once
- The last graph is a function, although discontinuous, for the same reason.
Angle 4 would be 77degrees because angle two is vertical to angle four.
Angle 3 and Angle 1 are equal because they are vertical to each other.
You would subtract 180 (degrees) minus 77 (degrees) and get 103 (degrees).
So Angle 3 and Angle 1 would both be 103 degrees.
You would get 180 degrees from the line.