Question

用绳量一棵树,用绳子饶树干5圈,测得5圈绳长共47.1分米,树干的横截面的面积是多少平方分米

Answer 1

半径=47.1/5/3.14/2

=9.42/3.14/2

=3/2

=1.5分米

面积=1.5*1.5*3.14

=2.25*3.14

=7.065平方分米

答：树干的横截面的面积是7.065平方分米.