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A metallic solid consists of a cone and a hemisphere. The height of the cone is 24 cm and the diameter of the base is 14 cm.

(a) How do you find the slant height of the cone when the vertical height and diameter of the base are given? Write it.

(b) Find the volume of the solid.

(c) If the solid object was melted and turned into a cylindrical object of radius 7 cm, what is the height of the cylinder? Calculate it.


Sagot :

Alright, let's go through each part of the problem step-by-step:

### Part (a): Finding the Slant Height of the Cone

Given:
- Height of the cone ([tex]\( h \)[/tex]) = 24 cm
- Diameter of the base = 14 cm
- Therefore, the radius of the base ([tex]\( r \)[/tex]) = 14 / 2 = 7 cm

To find the slant height ([tex]\( l \)[/tex]) of the cone, we use the Pythagorean theorem:
[tex]\[ l = \sqrt{r^2 + h^2} \][/tex]

Substitute the values:
[tex]\[ l = \sqrt{7^2 + 24^2} \][/tex]
[tex]\[ l = \sqrt{49 + 576} \][/tex]
[tex]\[ l = \sqrt{625} \][/tex]
[tex]\[ l = 25 \text{ cm} \][/tex]

So, the slant height of the cone is 25 cm.

### Part (b): Finding the Volume of the Solid

The solid consists of a cone and a hemisphere.

1. Volume of the Cone:
[tex]\[ V_{\text{cone}} = \frac{1}{3} \pi r^2 h \][/tex]

Substitute the values:
[tex]\[ V_{\text{cone}} = \frac{1}{3} \pi (7^2) (24) \][/tex]
[tex]\[ V_{\text{cone}} = \frac{1}{3} \pi (49) (24) \][/tex]
[tex]\[ V_{\text{cone}} = \frac{1}{3} \pi (1176) \][/tex]
[tex]\[ V_{\text{cone}} \approx 1231.50 \text{ cm}^3 \][/tex]

2. Volume of the Hemisphere:
[tex]\[ V_{\text{hemisphere}} = \frac{2}{3} \pi r^3 \][/tex]

Substitute the values:
[tex]\[ V_{\text{hemisphere}} = \frac{2}{3} \pi (7^3) \][/tex]
[tex]\[ V_{\text{hemisphere}} = \frac{2}{3} \pi (343) \][/tex]
[tex]\[ V_{\text{hemisphere}} \approx 718.38 \text{ cm}^3 \][/tex]

3. Total Volume of the Solid:
[tex]\[ V_{\text{solid}} = V_{\text{cone}} + V_{\text{hemisphere}} \][/tex]
[tex]\[ V_{\text{solid}} \approx 1231.50 \text{ cm}^3 + 718.38 \text{ cm}^3 \][/tex]
[tex]\[ V_{\text{solid}} \approx 1949.88 \text{ cm}^3 \][/tex]

So, the total volume of the solid is 1949.88 cm³.

### Part (c): Finding the Height of the Cylinder

When the solid is melted and reformed into a cylinder with a radius of 7 cm, we use the total volume calculated above to find the height of the cylinder.

Given:
- Volume of the cylinder ([tex]\( V_{\text{cyl}} \)[/tex]) = Volume of the solid
- Radius of the cylinder ([tex]\( r_{\text{cyl}} \)[/tex]) = 7 cm

[tex]\[ V_{\text{cyl}} = \pi r_{\text{cyl}}^2 h_{\text{cyl}} \][/tex]

Substitute the values:
[tex]\[ 1949.88 = \pi (7^2) h_{\text{cyl}} \][/tex]
[tex]\[ 1949.88 = \pi (49) h_{\text{cyl}} \][/tex]
[tex]\[ h_{\text{cyl}} = \frac{1949.88}{\pi (49)} \][/tex]
[tex]\[ h_{\text{cyl}} \approx 12.67 \text{ cm} \][/tex]

So, the height of the cylinder is approximately 12.67 cm.