一个圆柱体的侧面展开为正方形,已知它的一个底面圆为的面积是5平方米,这个圆柱体的表面积是多少

圆的面积公式是 S＝πr²
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所以底面圆的半径是r=√5/π (m)

圆的周长公式是 C=2πr
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然后可以求出底面圆的周长是C=2π√5/π (m)
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因为侧面展开图正方形 所以这个圆柱的高也是2π√5/π (m)
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那么圆柱的侧面积是 S侧=2π√5/π * 2π√5/π = 20π (m²)

圆柱的底面积由题可知为5(m²)

所以这个圆柱的全面积是 S表=20π+2*5=20π+10≈72.8(m²)

好久没做这种题了..
公式都快忘记了...

答案的空格会被隐藏掉 我根号不会打
所以为了让答案看的清楚点 我把空格换成`了..