Հարց 81

A circle has a radius of 10 centimetres, and π is to be taken as exactly 3.14. Select all the statements that are true about the area of this circle.

Its area is 314 square centimetres.Ճիշտ պատասխան
Its area is 62.8 square centimetres.
Its area is 314 centimetres.
Its area has to be reported in square units rather than plain centimetres, because two lengths were multiplied.Ճիշտ պատասխան

Բացատրություն

Squaring the 10 gives 100, and 3.14 lots of 100 measure the surface enclosed. The value 62.8 comes from the rule for the way round the edge, which multiplies by the width instead of by the radius times itself, and a boundary length answers a different question entirely.

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