Quanto mede o lado do quadrado?

Designado por $r$ o comprimento do lado do quadrado, em metros, temos:

$$\begin{array}{*{20}{l}} {{A_{Clara}} = 4,35}& \Leftrightarrow &{\begin{array}{*{20}{c}} {{r^2} – \frac{1}{4}\pi  \times {r^2} = 4,35}& \wedge &{r > 0} \end{array}}\\ {}& \Leftrightarrow &{\begin{array}{*{20}{c}} {4{r^2} – \pi  \times {r^2} = 17,4}& \wedge &{r > 0} \end{array}}\\ {}& \Leftrightarrow &{\begin{array}{*{20}{c}} {\left( {4 – \pi } \right){r^2} = 17,4}& \wedge &{r > 0} \end{array}}\\ {}& \Leftrightarrow &{\begin{array}{*{20}{c}} {{r^2} = \frac{{17,4}}{{4 – \pi }}}& \wedge &{r > 0} \end{array}}\\ {}& \Leftrightarrow &{\begin{array}{*{20}{c}} {r =  \pm \sqrt {\frac{{17,4}}{{4 – \pi }}} }& \wedge &{r > 0} \end{array}}\\ {}& \Leftrightarrow &{r = \sqrt {\frac{{17,4}}{{4 – \pi }}} } \end{array}$$

Portanto, $r \approx 4,5$ cm.