Math  /  Geometry

QuestionGiven a cone with a height or radius of 18yd18 \, \text{yd}, find the surface area and volume of the cone. Use the following formulas:
1. Surface Area (AA) of a cone: $ A = \pi r (r + \sqrt{h^2 + r^2}) \] where \(r\) is the radius of the base and \(h\) is the height.
2. Volume (VV) of a cone: $ V = \frac{1}{3} \pi r^2 h \]
Determine whether the given measurement of 18yd18 \, \text{yd} is the radius or the height, and use it to calculate the surface area and volume. If only one measurement is given, assume it is the radius and provide the formulas for both scenarios.

Studdy Solution

STEP 1

What is this asking? We need to find the surface area and volume of a sphere, given its diameter. Watch out! The image shows a diameter, not a radius!
Don't forget to divide the diameter by two to get the radius.
Also, don't mix up the formulas for surface area and volume!

STEP 2

1. Calculate the radius.
2. Calculate the surface area.
3. Calculate the volume.

STEP 3

The **diameter** is given as 1818 yd.
Since the radius is half the diameter, we **divide** the diameter by 22 to get the radius.
This is because the diameter spans the entire circle, while the radius is the distance from the center to the edge, which is half the distance across.

STEP 4

Radius=Diameter2 \text{Radius} = \frac{\text{Diameter}}{2} r=18 yd2=9 yd r = \frac{18 \text{ yd}}{2} = \mathbf{9 \text{ yd}} So, our **radius**, rr, is 9\mathbf{9} yd.

STEP 5

Now, let's **calculate** the surface area of the sphere.
The formula for the surface area of a sphere is A=4πr2A = 4 \pi r^2, where rr is the radius.
This formula tells us how much "skin" it would take to perfectly cover the entire sphere.

STEP 6

We **plug in** our radius, 9\mathbf{9} yd, into the formula: A=4π(9 yd)2 A = 4 \cdot \pi \cdot (9 \text{ yd})^2 A=4π81 yd2 A = 4 \cdot \pi \cdot 81 \text{ yd}^2 A=324π yd2 A = 324\pi \text{ yd}^2 So, the **surface area** is 324π\mathbf{324\pi} square yards.

STEP 7

Finally, let's **calculate** the volume!
The formula for the volume of a sphere is V=43πr3V = \frac{4}{3} \pi r^3, where rr is the radius.
This formula tells us how much space is inside the sphere.

STEP 8

We **plug in** our radius, 9\mathbf{9} yd, into the formula: V=43π(9 yd)3 V = \frac{4}{3} \cdot \pi \cdot (9 \text{ yd})^3 V=43π729 yd3 V = \frac{4}{3} \cdot \pi \cdot 729 \text{ yd}^3 V=47293π yd3 V = \frac{4 \cdot 729}{3} \pi \text{ yd}^3 V=29163π yd3 V = \frac{2916}{3} \pi \text{ yd}^3 V=972π yd3 V = 972\pi \text{ yd}^3 So, the **volume** of the sphere is 972π\mathbf{972\pi} cubic yards.

STEP 9

The surface area of the sphere is 324π324\pi square yards, and the volume is 972π972\pi cubic yards.

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