The inner side of the innermost runway is 400 meters long, that is, the arc length of two semicircles plus two lengths of a rectangle, that is, the circumference of a circle with a radius of 60 meters plus two lengths of a rectangle. To find the length of a rectangle, subtract the circumference of the circle from 400 meters and divide it by 2. To ask "how many meters is the inner edge of the outermost runway", first ask the radius of the outermost circle, and then use the circumference of the outermost circle+two lengths of the rectangle.

answer

Solution:

(1) Because the perimeter of the innermost runway =2× the length of the straight runway+the perimeter of two semi-circles,? So the length of the straight runway = (the perimeter of the innermost runway-the perimeter of two semi-circles) ÷2.

(400-3. 14×60)÷2

=2 1 1.6÷2

=105.8m

Answer: The length of the straight runway is105.8m..

(2) 105.8×(60+2×6× 1)+3. 14×(60÷2+6× 1)?

=76 17.6+4069.44

= 1 1687.04 m2

A The sports ground covers an area of 1 1687.04 square meters.