Question

Help with these geometry problems, please! 10th grade geometry

Answer 1

Question 2: 320.48 in^2

Question 3: 6.28 in^3

Explanation:

Question 2)

The question tells us that the shape will be covered in paint. This means that we need to find the surface area instead of volume. In the question, I’ll find the surface area of the two individual shapes (The cylinder and the rectangular prism) and take away parts that will not be covered in paint.

Rectangular Prism

1. ((10x10)+(10x3)+(10x3))x2 — All rectangular prisms have 2 sides with the same area. Since there are 6 sides total, all we need to do is find 3 sides of different sizes and multiply them by 2. The number we get is 320 in^2.

2. We will not be painting the bottom, so we can take the area of the bottom away. The area of the bottom is 10x10, which is 100. 320 - 100 is 220 in^2.

3. We are also not painting the area where the cylinder is touching the top (The circle-shaped area). The formula of finding the area of a circle is radius x radius x pi. Since the radius is 4 and pi can be rounded to 3.14, the area of the circle will be 4x4x3.14, which is 50.24 in^2. We can take that away from 220, so 220 - 20.24 is 169.76 in^2.

Cylinder

1. 4x4x3.14 — We know that one side of the cylinder (The base) will not be painted, so all we need to do is find the area of one of the bases. Radius x Radius x pi, in this case, is 50.24 in^2.

2. (((4+4)x3.14)x6) — Now we need to find the area of the side of the cylinder. The area of the side is base x height. The base length is the perimeter of the circle. The equation of the circle perimeter is (radius + radius) x pi. In numbers, it will be 8x3.14 which is 25.12. The height of the side is 6, so the equation will be 25.12 x 6, which is 150.72.

3. The surface area of the cylinder (excluding the base at the bottom) is 150.72 in^2.

Since the rectangular prism and the cylinder is stuck together and is considered as a whole, we add the two numbers together. 169.76 + 150.72 = 320.48 in^2!

Question 3)

The amount of water the cups can hold is the same size as the volume of individual cups. In order to find out the amount of water each cup can hold, we need to find the volume first.

Cup #1

1. (2x2x3.14)(2.25) — This is the base times the height of the bottom cylinder. The formula to find a circle is radius x radius x pi, and the height was 2.25. The volume of this shape will be 28.26 in^3.

2. (3x3x3.14)(1.5) — The area of the bottom is radius x radius x pi, and the height was 1.5 If we multiply all of these numbers together, we get 42.39 in^3.

3. Now that we found the two cylinders of the first cup, we can add them together. 28.26 + 42.39 = 70.65.

4. The area of cup #1 is 70.65 in^3.

Cup #2

1. (3.5 x 3.5 x 3.14)(6)(1/3) — The formula for finding the area of a cone is base x height x 1/3. The area of the base is radius x radius x pi, and the height is 6. Then we multiply by 1/3 (or divide by 3). Then, we get 76.93 in^3.

2. The volume of cup #2 is 76.93 in^3.

The question asks: How much more water will the larger cup hold?

Comparing 70.65 in^3 (First cup) and 76.93 in^3 (Second cup), we know that the second cup is bigger. To find the difference in the amount of water it can hold, we can subtract 70.65 from 76.93. This equals 6.28 in^3.

The final answer for Question 3 will be 6.28 in^3!

Answer 2

Explanation:

3.

the left cup is the summary of 2 cylinders.

the right cup is just a cone.

the volume of a cone is

pi×r²×h/3 = pi×3.5²×6/3 = pi×12.25×2 = pi×24.5 =

= 76.93 in³

the volume of a cylinder is

pi×r²×h

the first cylinder is

pi×3²×1.5 = pi×9×1.5 = pi×13.5 = 3.14×13.5 = 42.39 in³

the second cylinder is

pi×2²×2.25 = pi×4×2.25 = pi×9 = 28.26 in³

in total the cup has

42.39 + 28.26 = 70.65 in³

so, the cone has the larger volume by 6.28 in³ ≈ 6 in³.

that would be 3.479827 fl.oz. ≈ 3 fl.oz. of water.

I have no idea on what scale you need to quantify the amount of water. I just guessed.

2.

here we need the surface area.

the object consists of a large prism (or block) and a cylinder.

we don't need the bottom area for neither, as the cylinder is simply on top of the prism, and its bottom is not going to be painted either.

we need 5 sides of the prism :

front and back

left and right

top (and we need the full top, because the area the cylinder is covering up is the same area for the top of the cylinder).

and the we need to add only the side wall of the cylinder the "mantle".

so,

front and back rectangles are 10×3 × 2 = 60 in²

left and right rectangles are 10×3 × 2 = 60 in²

the top rectangle (square) is 10×10 = 100 in²

the cylinder mantle is

circumference of the circle × height

2×pi×r×h = 2×pi×4×6 = 3.14×48 = 150.72 in²

so, in total we have

60 + 60 + 100 + 150.72 = 370.72 in² ≈ 371 in²