What exactly do you need help with?
The earth's circumference is: 24,901miles
Answer:
Yes. No graph paper.
Step-by-step explanation:
Let's say the 3 points are A, B, C.
If A, B and C lie on one line then 

Hence, they lie on one line.
You don't need to use a graph paper to prove it.
Answer:
The cable is 5 Meters long.
Step-by-step explanation: