(1)S=∏r^2 (2)S=∏r^2
=∏(6÷2)^2 =∏(25.12÷∏÷2)^2
=9∏ =∏4^2
=28.26(cm^2) =16∏
C=∏d =50.24
=6∏
=18.84(cm)
己知d=6厘米,求这个圆的周长和面积.己知C=25.12厘米,求这个圆的面积.
(1)S=∏r^2 (2)S=∏r^2
=∏(6÷2)^2 =∏(25.12÷∏÷2)^2
=9∏ =∏4^2
=28.26(cm^2) =16∏
C=∏d =50.24
=6∏
=18.84(cm)