Its is 9 cm. I know because the 13 cm side isn't equivalent to the 13 cm side so if you measure it like i did you will get the answer 9cm.
2r=R
Because 2 of "r" make 1 R
You can use properties to solve equations with variables on both side by simplifying get the variable on one side. solve using inverse operations then check to see if it fits in right .
This question says that its 3/4 of 24, thats would be 18.... and since they need 13 they're done! :)
