1. I first grabbed a ruler to measure the other straight side of the figure.
2. Both of the straight sides were 3 cm so I knew that the answer had to be greater than 6 cm.
3. I then estimated that the other side was longer than the 3 cm.
4. I then had to my logic to figure out the answer and I very quickly realized that 4.7 cm would not make since because that is less than 6 cm. I know 7.7 cm would not make since because I knew the curved side was longer than 3 cm not shorter. 18.8 cm did not make since because that answer has WAY to much cm. Using the process of elimination, 10.7 cm was the only answer that made since.