2r*2r-3.14*r*r
=4r2-3.14r2
=0.86r2
4r2-3.14r2=(4-3.14)r2=0.86r2
原式=r×r(4-3.14)
??????=0.86r×r
0
2r*2r-3.14*r*r
=4r2-3.14r2
=0.86r2
4r2-3.14r2=(4-3.14)r2=0.86r2
原式=r×r(4-3.14)
??????=0.86r×r