黄冈小状元人教版数学六年级下册第8页答案!急

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黄冈小状元人教版数学六年级下册第8页答案!急
黄冈小状元人教版数学六年级下册第8页答案!急

黄冈小状元人教版数学六年级下册第8页答案!急
一,6.28 9.42 12.56 15.7 18.84 21.98 25.12 28.26
二,8 125.6 50.24 226.08 5 314 78.5 471
三,
S侧=πdh
=3.14x6x2.6
=18.84x2.6
=48.984(dm²)
答:需要铝皮48.984dm².
r=6÷2=3(dm)
S底=πr²
=3.14x3²
=3.14x9
=28.26(dm²)
28.26x2=56.52(dm²)
答:需要羊皮56.52dm².
四,
S侧=πdh
=3.14x6x1.2
=18.84x1.2
=22.608(m ²)
r=6÷2=3(m)
S底=πr²
=3.14x3²
=3.14x9
=28.26(m²)
S总=S侧+S底
=22.608+28.26
=50.868(m ²)
答:50.868m ²
五,
S侧=πdh
=3.14x0.6x1
=1.884x1
=1.884(m ²)
r=0.6÷2=0.3(m)
S底=πr²
=3.14x0.3²
=3.14x0.9
=0.2826(m²)
0.2826x2=0.5652(m²)
0.5652+1.884=2.4492(m²)
2.4492x0.2≈0.49(kg)
答:大约需要防锈油漆0.49kg.
六,
S侧=2πrh
=6.28x3x10
=18.84x10
=188.4(cm²)
1平方米=10000平方厘米
10000÷188.4≈53(个)
答:最多能做53个.
七,
S侧=πdh
=3.14x1.8x5
=5.652x5
=28.26(m²)
28.26x20=565.2(m²)
答:面积是565.2m².
培优作业
八,
r=C÷π÷2
=18.84÷3.14÷2
=6÷2
=3(dm)
d=3x2=6(dm)
10-6=4(dm)
S侧=ch
=18.84x4
=75.36(dm²)
S底=πr²
=3.14x3²
=3.14x9
=28.26(dm²)
S表=S侧+S底x2
=75.36+28.26x2
=75.36+56.52
=131.88(dm²)
答:是131.88dm².
第九页也送给你.
一,3.92m² 96dm² 273.18cm²
二,2 3 2
三,
10x五分之六=12(cm)
r=10÷2=5(cm)
S侧=πdh
=3.14x10x12
=31.4x12
=376.8(cm²)
S底=πr²
=3.14x5²
=3.14x25
=78.5(cm²)
S总=S侧+S底
=376.8+78.5
=455.3(cm²)
答:需要455.3cm²的不锈钢薄板.
四,
15x三分之一=5(cm)
S侧=πdh
=3.14x6x5
=18.84x5
=94.2(cm²)
答:是94.2cm².
五,
d=8x2=16(cm)
S长=16x6
=96(cm²)
96x2=192(cm²)
答:增加192cm².
六,
r=C÷π÷2
=15.7÷3.14÷2
=5÷2
=2.5(cm)
S侧=ch
=15.7x15.7
=246.49(cm²)
S底=πr²
=3.14x2.5²
=3.14x6.25
=19.625(cm²)
S表=S侧+S底x2
=246.49+19.625x2
=246.49+39.25
=285.74(cm²)
答:285.74cm².
七,
4-1=3(次)
3x2=6(个)
S底=18.84÷6=3.14(dm²)
r²=3.14÷3.14
=1(dm²)
r=1÷1=1(dm)
C=2πr
=6.28x1
=6.28(dm)
S侧=ch
=6.28x20
=125.6(dm²)
S表=S侧+S底x2
=125.6+3.14x2
=125.6+6.28
=131.88(dm²)
答:表面积为131.88dm².
培优作业
八,
C=S侧÷h
=3.14÷5
=6.28(cm)
r=c÷π÷2
=6.28÷3.14÷2
=2÷2
=1(cm)
S侧=2πrh
=6.28x1x20
=6.28x20
=125.6(cm²)
S底=πr²
=3.14x1²
=3.14x1
=3.14(cm²)
S表=S侧+S底x2
=125.6+3.14x2
=125.6+6.28
=131.88(cm²)
答:原来是131.88cm².

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