Shakira needs a total of 239.5 approximately 240 sq. ft of sod to cover the backyard.
Let us analyse the given diagram:
We can divide the given diagram in three parts:
Part I: Rectangle having length 20' and with 12'
As we know,
Area of rectangle = length
width
So, the area of the rectangle will be:
![20' * 12'= 240 \: ft^2](https://img.qammunity.org/2021/formulas/mathematics/middle-school/niszrxxs44z2kp5h8sik1yak6pb4wi63y2.png)
Part II: Triangle having base 8' and height 12'
As we know,
Area of right angle triangle =
![(1)/(2)* base * height](https://img.qammunity.org/2021/formulas/mathematics/middle-school/jhoxujgz2angaba70fkfepap0k990f0iht.png)
So, the area of the triangle will be:
![(1)/(2)* 8 * 12 = (96)/(2) = 48\:ft^2](https://img.qammunity.org/2021/formulas/mathematics/middle-school/s2vyxo7f4rz3bztkdvk0c7a1fnzdwsq6ux.png)
Part III: lower triangle having base 3' and height 20'
Area of right angle triangle =
![(1)/(2)* base * height](https://img.qammunity.org/2021/formulas/mathematics/middle-school/jhoxujgz2angaba70fkfepap0k990f0iht.png)
So, the area of the triangle will be:
![(1)/(2)* 3 * 20 = (60)/(2) = 30\:ft^2](https://img.qammunity.org/2021/formulas/mathematics/middle-school/tverma7v8ud3hh2wzv4uj3yn6n5ux5c893.png)
Part 4: Area of circle which is uncovered having radius = (10/2) = 5 ft
As the area of circle =
![\Pi r^2](https://img.qammunity.org/2021/formulas/mathematics/middle-school/q4232fgp1bx4g65pnl70qh0futy2mephqi.png)
So, area of circle will be
![3.14 * 5 * 5 = 78.5 \:ft^2](https://img.qammunity.org/2021/formulas/mathematics/middle-school/ie61hiplxm36a8p4zga2nb23tyzwzxbjbx.png)
Now total shaded area will be:
![240+48+30-78.5=239.5 \:ft^2](https://img.qammunity.org/2021/formulas/mathematics/middle-school/flfcwidxwjinhzxj5dho65trr4tmififit.png)