At the beginning of six people, the actual radius surrounded by everyone is 70cm, and the circumference of the actual circle is 140π cm ... The distance (arc) between every two people is 140π/6 = 70/3π cm,

There are eight people now, and the distance (arc) between them is still 70/3π cm. At this time, the actual circumference is 70/3π times 8=560π/3, and the central angle formed between every two people is n = 360/8 = 45.

L = 2π rn/360 = π rn/ 180 (r = radius, n= absolute value of arc angle).

Substituting into the formula gives r = 280/3cm.

Backward distance =R-70=70/3cm.

You bring it in and do the math yourself. .