where's the rest of question so I can help?
If There is a math equation you can use math-way.
Also it would help if you can take a better picture.
Once you take a better picture I promise i will try my best to answer the question.
Answer:
The length of a pen.
Step-by-step explanation:
A length of a pen is around three inches and is reasonable but all of the others are way too big and can be measured in feet or miles.
It equals 45 degrees because if you have a ~ line it means you have 45 degrees and don't forget to thank me
