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 area of $I,II,III,IV,V$

$=16+4\times 10=56$ sq. cm