Math problem! The bottom of the cake box is 40cm in diameter and 15cm in height. Tie it with a ribbon and tie it at the center of the circle. The knotted part is 28cm long. What is the total length of the rope? Math problem! The bottom of the cake box is 40cm in diameter and 15cm in height. Tie it with a ribbon and tie it at the center of the circle. The knotted part is 28cm long. What is the total length of the rope?

Analysis: the total length of the rope = the length of the knotted part+the diameter length of the four bottom surfaces (the upper and lower sides of the cake)+four heights (except the upper and lower sides, the rest are heights).

Known knotted part length =28cm.

Total length of upper and lower ropes = bottom diameter+bottom diameter+bottom diameter = 40+40+40 = 160cm.

The rest length =4, the height length =15+15+15 = 4×15 = 60 cm.

Add the three values to get the total length: 28+ 160+60=248cm.

So the total length of the rope = 248 cm.

This problem is easy to forget the length of the knotted part or not to think that the length of the rope has four heights, which is easy to make mistakes.