Question

圆的应用题~~~1.小圆直径是大圆的4分之3,大圆周长是25012厘米,小圆面积是多少平方厘米?2.一个正方形面积是20

Answer 1

1.2πR=25012

R=12506/π

r=(3/4)*R=18759/(2π)

S=πr^2=π*(18759/(2π))^2=18759^2/(4π)≈28003318.68

2.设正方形边长为a

S=a^2=20

a=√20=2√5

Rmax=a/2=√5

Smax=πRmax^2=5π

3.S三角形=1/2×底×高

S三角形=12.5