Question

Oblicz pole koła, którego obwód ma długość
10π cm
16π m
1,8π mm
5π dm

Answer 1

2πr=10π /:2π
r=5
P=πr²
P=25π cm²

2πr=16π/:2π
r=8
P=64π m²

2πr=1,8π /:2π
r=0,9
P=0,81π mm²

2πr=5π /:2π
r=2,5
P=6,25π dm²

Answer 2

P = πr^2
Obw = 2πr

2πr = 10π cm
2r = 10 r = 5
P = 25π cm^2

2πr = 16π m
r = 8 m
P = 64π m^2

2πr = 1,8π mm
r= 0,9 mm
P = 0,81 π mm^2

2πr = 5π dm
r = 2,5 dm
P = 6,25 π dm ^2

Answer 3

P=π*r²
Ob=2π*r
r=Ob/2π

A) Ob=10π cm
r=10π cm/2π
r=5cm
P=π*5²=25π cm²

B) Ob=16π m
r=16π m/2π
r=8m
P=π*r²=π*8²=64π m²

C) Ob=1,8π mm
r=1,8π mm/2π
r=0,9mm
P=π*r²=π*0,9²=0,81π mm²

D) Ob=5π dm
r=5π/2π
r=2,5dm
P=π*r²=π*2,5²=6,25π dm²