Question

I have no idea, on how to do this maths question

Answer 1

To calculate the shaded area, first, we need to calculate the area of the square and then, we have to subtract to it the area of the circle.

The area, A, of a square is computed as follows:

$A=a^2$

where a is the length of each side.

Substituting with a = 18 cm, we get:

$\begin{gathered} A_1=18^2 \\ A_1=324\operatorname{cm}^2 \end{gathered}$

The area, A, of a circle is computed as follows:

$A=\frac{\pi D^2}{4}$

where D is the diameter of the circle.

Substituting with D = 18 cm, we get:

$\begin{gathered} A_2=\frac{\pi\cdot18^2}{4} \\ A_2=\frac{3.142\cdot324}{4}\text{ (Using }\pi=3.142) \\ A_2=254.502\operatorname{cm}^2 \end{gathered}$

Finally, the shaded area is:

$\begin{gathered} \text{ Shaded area = }A_1-A_2 \\ \text{ Shaded area = }324-254.502 \\ \text{ Shaded area = }69.498\operatorname{cm}^2 \end{gathered}$