Answer:
-
![s=(P)/(3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/tdkj2z5rxkmjbakgd5qyi5nw4o9uryx0qp.png)
- Dimensions of the flag:
![lenght=6.65\ ft\\\\width=3.5\ ft](https://img.qammunity.org/2020/formulas/mathematics/middle-school/5yv30g63k7qz1x3sqhk6gjo5isgywx93mq.png)
- Area of the flag:
![23.275\ ft^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/k3f1w2d73241izqf9gnkhnfikv2frd3y9r.png)
Explanation:
The missing figure of the exercise is attached.
We know that the perimeter of the triangle is given by:
![P= 3s](https://img.qammunity.org/2020/formulas/mathematics/middle-school/63o2aou5h5806jiu2lz9clg7zvhfmg0lvp.png)
Where "s" is the side lenght of the triangle.
Solving for "s", we get:
![s=(P)/(3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/tdkj2z5rxkmjbakgd5qyi5nw4o9uryx0qp.png)
Therefore, if the perimeter of the triangle is 126 inches, its side length is:
![s=(126\ in)/(3)\\\\s=42\ in](https://img.qammunity.org/2020/formulas/mathematics/middle-school/qc7b2veqdmebq0y8q9u4y54vm589jcov3y.png)
Since
, we know that "s" in feet is:
![s=(42\ in)((1\ ft)/(12\ in))=3.5\ ft](https://img.qammunity.org/2020/formulas/mathematics/middle-school/5rdj5lj7bick0hgwu1s3zetusosm21jchu.png)
The area of a rectangle can be calculated with this formula:
![A=lw](https://img.qammunity.org/2020/formulas/mathematics/middle-school/6ha4hehcoeuii45f92n9qa4p9h4g0r5n0e.png)
Where "l" is the lenght and "w" is the width
We can observe in the figure that the lenght and the width of the flag are:
![l=1.9s\\w=s](https://img.qammunity.org/2020/formulas/mathematics/middle-school/glj9uj23odc4z6jx99ni7pn0g9s8z36qu6.png)
Then, the dimensions of the flag are:
![l=1.9(3.5\ ft)=6.65\ ft\\w=3.5\ ft](https://img.qammunity.org/2020/formulas/mathematics/middle-school/af5kdhzkobwzzyww6g4w6p11bpfcivny7i.png)
And the area is:
![A=(6.65\ ft)(3.5\ ft)=23.275\ ft^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/lsbq46vdydlmarnnmpi5yn3r7fgsh3wm2u.png)