Question

Sara has designed the blades of a windmill as shown in the diagram above, the total area(in sq. cm) covered by the blades is.

• A. 56

Answer 1

The correct option is A 56
Here, let's mark the different shapes for a better understanding as shown.
On observation, we can conclude $I$ is a square, and $II,III,IV\&V$ are right triangles with the same dimensions.
$\therefore$ Areas of $II,III,IV\&V$ will be equal.
Now, Area $\left(I\right)={\text{Side}}^2$
$=4^2=16$ sq. cm.
And for the right triangles as shown in the figure $II$
Base $=4$ cm,
Height $=5$ cm.
$\therefore$ Area of the right triangle $=\frac{1}{2}\times 4\times 5=10$ sq. cm
$\therefore$ Total area covered by the windmill
Sum of Areas of $I,II,III,IV,V$
$=16+4\times 10=56$ sq. cm