The relation you have shown is not a function.
In order to be a function, a relation's domain must be continuous in that no x-value is not repeated in any of the points. Since the first two points of the relation are (5,1) and (5,3), you can see that they have the same x-value, meaning that this is not a function.
One quick way you could test this is to quickly sketch a graph and use the vertical line test to see if the relation in question is a function. If it cross the vertical line once in all places, it is a function - if it crosses the vertical line more than once in any place, it is not a function.
Answer:
The length of the diagonal HJ is 10.82 units
Step-by-step explanation:
* Lets revise the rule of the distance between two points
- 
, where
and 
are the two points
* Lets use this rule to find the length of the diagonal HJ
∵ The coordinates of point H are (-4 , 3)
∵ The coordinates of point J are (5 , -3)
∴ 
and 
∴ 
and 
- Lets find the length of the diagonal HJ by using the rule above
∴ HJ = 
∴ HJ = 
∴ HJ = 10.82
* The length of the diagonal HJ is 10.82 units
