Answer:
Hi! They most likely ran your answer through a copywrite website or just googled your answer and that's how they found out you cheated. Therefore, they probably know what site you copied the answer from. Sorry hun!
If it was a math problem then was it just an equation with the answer in number form? If so, then she probably could only tell what you copy and pasted. So she'll most likely be able to see that you didn't just copy and paste a division symbol...
In conclusion, either way she knows you cheated. Next time, re- word as much as you can and type everything out yourself! Good luck hun!