Step-by-step explanation
The question wants us to obtain the perimeter of the paperboard that remains after the semicircle has been removed
To do so, we will follow the steps below:
Step1: Find the Perimeter of the rectangle
The perimeter of a rectangle is simply the sum of all its sides
So in our case, we will have to sum sides A as given below
![Perimeter\text{ of rectangle= 21 +33+33= 87 inches}](https://img.qammunity.org/2023/formulas/mathematics/college/uc9ef10iknvxns0wgtavkv6h8psix8skz8.png)
Step 2: Find the perimeter of the semi-circle
The perimeter of a semi-circle is given by:
![\begin{gathered} (\pi D)/(2) \\ where \\ \pi=3.14 \\ D=diameter\text{ of the semicircle =21 inches} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/o2369jz0yk3xurwadey3t487w6k3zt7we9.png)
Simplifying
![Perimeter\text{ of semicircle=}(3.14*21)/(2)=32.97\text{ inches}](https://img.qammunity.org/2023/formulas/mathematics/college/byv8vqnwmx9smuo3e9qwupfd6ty12so5wc.png)
Step 3: Find the sum of the perimeters of the rectangle and semicircle
Therefore, the perimeter of the paperboard that remains after the semicircle is removed will be
![\begin{gathered} perimeter\text{ }of\text{ }the\text{ }rectangle+\text{ perimeters of the semicircle =87inches + 32.97 inches} \\ perimeter\text{ }of\text{ }the\text{ }rectangle-\text{ perimeters of the semicircle =119.97 inches} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/uk57dj41edba4q4ohiwm57msevsnis1ka0.png)
Hence, the perimeter of the paperboard that remains after the semicircle is removed will be 119.97 in