The flat swing has not yet risen, but the pedal is one foot off the ground.

The swing on the ground has not yet risen, the pedals are one foot off the ground, and I see off two steps in line with the people. It is remembered that a person of five feet is taller; the ladies and beauties are competing for the ball, and the whole day is full of jokes. The good teacher is always curious and figures out How long is the cable?

(Note: 1 step = 5 feet in ancient times)

Translated into modern language, the general meaning is:

The height of the pedal from the ground when the swing is hanging quietly. It's 1 foot. Now take two steps, and someone records that the height of the pedal from the ground is 5 feet. Ladies and beauties competed to swing on the swing, laughing and laughing all day long; the master craftsmen were curious about how long the rope of the swing was?

Answer: It can be calculated that the chord length of the fan-shaped swing swing is square root (100 16) = 2 square root (29)

The perpendicular to the chord from the center of the circle is given by It can be seen that the chord tangent angle is equal to half of the central angle. The resulting right triangle is similar to the triangle where the chord tangent angle is located. From the proportion of the corresponding line segments, the radius (that is, the length of the rope) can be found as

L=R= 14.5 feet

That is, the length of the rope is 14.5 feet.