Sally had just got her license, and the first night her parents said she could drive, she came home, and her little dog ran in front of her. To avoid her dog, she smashed into the side of the house. After everyone was determined to be OK, she had the fun of repairing the damage to the house.



She offered to paint the side of the house for her parents. Her parents left it up to her to buy the paint and do all the work. Using her amazing Algebra 2 skills, she thought she’d calculate what to buy. The first step was to determine how much paint she would need.



First, she needed to determine the surface area of the side of the house in order to estimate the number of gallons of paint she would need. She knew the top of the house was an isosceles triangle. She figured she could climb on a ladder to measure the angle between the pitch of the roof and the wall, and the rest was pretty easy.



Using composite figures and trigonometry, she calculated the area of the side of the house. Image of the house with measurements



Next, she went to the local hardware store and learned that there are many different types of paint. So, she created a table to compare the different kinds and determine which would be best.



1) Calculate the square area of the side of the house. Image of the house with measurements.



2) Create your own table comparing the prices of paint. Choose three types of paint. Some might contain primer, a substance that helps the paint stick better and appear darker. These are often more expensive, but that would be one less coat of paint. You can use this sample table or make your own.

Sally had just got her license and the first night her parents said she could drive she came home and her little dog ran in

Answer :

1. Total Area of the Side of the House [tex]\[ \approx 394.696 \, \text{sq ft} \][/tex]

2. Paint Comparison:

| Paint Type | Price per Gallon | Gallons Needed | Total Cost |

|---------------------|------------------|----------------|------------|

| Standard Paint | $25 | 2 | $50 |

| Paint with Primer | $35 | 1 | $35 |

| High-Quality Paint | $45 | 1 | $45 |

Best Option: Paint with Primer - Total Cost: $35

This option is the most cost-effective.

Start by calculating the area of the side of the house using the given measurements and trigonometry.

1. Divide the shape into simpler figures:

- The side of the house consists of a rectangle at the bottom and an isosceles triangle at the top.

2. Calculate the area of the rectangle:

- The rectangle has a width of 35 ft and a height of 10 ft.

[tex]\[ \text{Area of the rectangle} = \text{width} \times \text{height} = 35 \, \text{ft} \times 10 \, \text{ft} = 350 \, \text{ft}^2 \][/tex]

3. Calculate the area of the isosceles triangle:

- To find the area of the isosceles triangle, we need to determine the base and the height.

- The given angle at the peak of the triangle is 117.2°.

- The two base angles of the isosceles triangle are each (180° - 117.2°) / 2 = 31.4°.

Draw a perpendicular from the peak of the triangle to the base, dividing the isosceles triangle into two right triangles. Each right triangle will have:

- One angle of 31.4°

- An adjacent side (half of the base of the isosceles triangle)

- A hypotenuse of 10 ft (height of the triangle)

Using trigonometry (specifically the sine function):

[tex]\[ \sin(31.4^\circ) = \frac{\text{opposite}}{\text{hypotenuse}} = \frac{\text{height}}{10 \, \text{ft}} \][/tex]

[tex]\[ \text{height} = 10 \, \text{ft} \times \sin(31.4^\circ) \][/tex]

Calculating the height:

[tex]\[ \text{height} \approx 10 \, \text{ft} \times 0.5214 \approx 5.214 \, \text{ft} \][/tex]

The base of the isosceles triangle is:

2 x (adjacent side) = 2 x (10 ft x cos(31.4°))

[tex]\[ \text{base} \approx 2 \times (10 \, \text{ft} \times 0.8572) \approx 2 \times 8.572 \, \text{ft} \approx 17.144 \, \text{ft} \][/tex]

The area of the isosceles triangle:

[tex]\[ \text{Area} = \frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times 17.144 \, \text{ft} \times 5.214 \, \text{ft} \][/tex]

[tex]\[ \text{Area} \approx \frac{1}{2} \times 89.392 \, \text{ft}^2 \approx 44.696 \, \text{ft}^2 \][/tex]

Calculate the total area of the side of the house:

Total area = Area of the rectangle + Area of the triangle = [tex]350 \, \text{ft}^2 + 44.696 \, \text{ft}^2 \approx 394.696 \, \text{ft}^2[/tex]

Create a table comparing the prices of different types of paint. For simplicity, assume the following types of paint:

| Paint Type | Price per Gallon | Coverage per Gallon (sq ft) | Contains Primer |

|---------------------|------------------|-----------------------------|-----------------|

| Standard Paint | $25 | 350 | No |

| Paint with Primer | $35 | 400 | Yes |

| High-Quality Paint | $45 | 450 | Yes |

Estimate the amount of paint needed based on the total area of 394.696 sq ft and compare the costs.

1. Standard Paint:

- Coverage per gallon: 350 sq ft

- Total area to be painted: 394.696 sq ft

- Number of gallons needed:

[tex]\[ \text{Number of gallons} = \frac{\text{Total area}}{\text{Coverage per gallon}} = \frac{394.696 \, \text{sq ft}}{350 \, \text{sq ft/gallon}} \approx 1.13 \, \text{gallons} \][/tex]

- Since you can't buy a fraction of a gallon, need 2 gallons.

- Cost:

Cost = 2 gallons x $25 per gallon = $50

2. Paint with Primer:

- Coverage per gallon: 400 sq ft

- Total area to be painted: 394.696 sq ft

- Number of gallons needed:

[tex]\[ \text{Number of gallons} = \frac{394.696 \, \text{sq ft}}{400 \, \text{sq ft/gallon}} \approx 0.99 \, \text{gallons} \][/tex]

- 1 gallon will be needed.

- Cost:

Cost = 1 gallon x $35 per gallon = $35

3. High-Quality Paint:

- Coverage per gallon: 450 sq ft

- Total area to be painted: 394.696 sq ft

- Number of gallons needed:

[tex]\[ \text{Number of gallons} = \frac{394.696 \, \text{sq ft}}{450 \, \text{sq ft/gallon}} \approx 0.88 \, \text{gallons} \][/tex]

- 1 gallon will be needed.

- Cost:

Cost = 1 gallon x $45 per gallon = $45

Comparison Table:

| Paint Type | Price per Gallon | Coverage per Gallon (sq ft) | Contains Primer | Gallons Needed | Total Cost |

|---------------------|------------------|-----------------------------|-----------------|----------------|------------|

| Standard Paint | $25 | 350 | No | 2 | $50 |

| Paint with Primer | $35 | 400 | Yes | 1 | $35 |

| High-Quality Paint | $45 | 450 | Yes | 1 | $45 |

Based on this comparison, Paint with Primer is the most cost-effective option since it only requires 1 gallon and has a total cost of $35.