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Вычисли приближённо площадь \(S\) круга диаметра \(d\) .

а) \(d=12\) см:

\(R= \dfrac{d}{2} =6\) см,

\(S= \pi R^2 \approx 3,14 \cdot 6^2 = 113,04\) см².

б) \(d=8\) см:

\(R=\) [ \(d^2\) | \(2d\) | \(\frac{d}{2}\) | \(\frac{d}{4}\) ] \(=\) [ ] см;

\(S=\) [ \(\pi R\) | \(2\pi d\) | \(\pi R^2\) | \(\pi d^2\) | \(2\pi R^2\) ] \(\approx\) [ ] \(=\) [ ]см².

в) \(d=4\) см:

\(R=\) [ \(d^2\) | \(2d\) | \(\frac{d}{2}\) | \(\frac{d}{4}\) ] \(=\) [ ] см;

\(S=\) [ \(\pi R\) | \(2\pi d\) | \(\pi R^2\) | \(\pi d^2\) | \(2\pi R^2\) ] \(\approx\) [ ] \(=\) [ ]см².

г) \(d=6\) см:

\(R=\) [ \(d^2\) | \(2d\) | \(\frac{d}{2}\) | \(\frac{d}{4}\) ] \(=\) [ ] см;

\(S=\) [ \(\pi R\) | \(2\pi d\) | \(\pi R^2\) | \(\pi d^2\) | \(2\pi R^2\) ] \(\approx\) [ ] \(=\) [ ]см².