Question

Zad 1. oblicz promienie kół o polach

a] 16pi cm2 b] 100pi m2 c] 0,04pi dm2 d] pi km2 e] 9/16 pi mm2

Zad 2. Oblicz pole koła

a) o promieniu 1,2m

b) o średnicy 3,6 dm

c) o obwodzie 4pi cm.

Help! ;d

Answer 1

P=πr²

a)16πcm²/:π

r²=16cm²

r=4cm

b)

100πm²/:π

r²=100m²

r=10m

c)

0,04πdm²/:π

r²=0,04dm²

r=0,2dm

d)

πkm²/: π

r²=1km²

r=1km

e)9/16π mm²/:π

r²=9/16mm²

r=3/4mm

 

2.

a)

r=1,2m

P=πr²

P=π*1,2²

P=1,44π m²

b)

r=3,6:2

r=1,8dm

P=π*1,8²

P= 3,24π dm²

c)

Ob=4π cm

2πr=4π/:2π

r-2cm

P=π2²

P=4π cm²

 

Answer 2

Zad.1
a)
16π = πr₂ /:π
r² = 16
r = 4 cm

b)

100π = πr² / :π
r² = 100
r = 10m

c)
0,04π = πr² /:π
r² = 0,04
r = 0,2dm

d)
πkm² = πr²
r = 1km

e)
9/16π = πr² /:π
r² = 9/16
r = 3/4
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Zad.2

1)
P = πr²
r = 1,2m
P = π(1,2m)²
P = 1,44πm²

2)
r = ½ * 3,6dm
r = 1,8dm
P = π(1,8dm)²
P = 3,24dm²

3)
Ob = 4πcm
Ob = 2πr
r = 2cm
P = π(2)²
P = 4πcm²