Question

Find the diameter of a circle with an area of804.25 cm?.Find the radius of a circle with a circumferenceof 28.27 km.

Answer 1

The area A of a circle with radius r is given by:

`A=\pi r^2`

Substitute A = 804.25 cm² into the equation above.

Therefore,

`\begin{gathered} 804.25=\pi r^2 \\ Hence \\ r^2=(804.25)/(\pi) \\ r=\sqrt{(804.25)/(\pi)}\approx16.00 \end{gathered}`

The diameter d of a circle of radius r is given by:

`\begin{gathered} d=2r \\ \end{gathered}`

Substituting r = 16, it follows that:

`d=2\left(16\right)=32cm`

Therefore, the diameter of the circle is 32 cm.

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