Math  /  Geometry

Questionh/public/activity/3006003/assessment 〔 3.6.3 Qulz: Spheres
Question 1 of 10 The area of a circle of radius 10 units is equal to the surface area of a sphere of radius 5 units. A. True B. False SUBMIT - PREVIOUS

Studdy Solution

STEP 1

What is this asking? Is the area of a circle with radius 1010 the same as the surface area of a sphere with radius 55? Watch out! Don't mix up area of a circle and surface area of a sphere!
Also, don't forget those squared terms!

STEP 2

1. Calculate Circle Area
2. Calculate Sphere Surface Area
3. Compare Results

STEP 3

Alright, let's **calculate the area** of this circle!
The formula for the area of a circle is πr2\pi \cdot r^2, where rr is the **radius**.
Remember, the radius is the distance from the center of the circle to any point on the edge.

STEP 4

We're given that the circle has a radius of 1010 units.
So, plugging that into our formula, we get: Areacircle=π(10)2 \text{Area}_{\text{circle}} = \pi \cdot (10)^2

STEP 5

Squaring 1010 gives us 100100, so the area of the circle is: Areacircle=100π \text{Area}_{\text{circle}} = 100 \cdot \pi We'll keep it in terms of π\pi for now to avoid rounding errors.

STEP 6

Now, let's tackle the **surface area** of the sphere!
The formula for the surface area of a sphere is 4πr24 \cdot \pi \cdot r^2, where rr is the **radius** of the sphere.

STEP 7

We know the sphere's radius is 55 units.
Let's plug that in: Areasphere=4π(5)2 \text{Area}_{\text{sphere}} = 4 \cdot \pi \cdot (5)^2

STEP 8

Squaring 55 gives us 2525, so: Areasphere=4π25 \text{Area}_{\text{sphere}} = 4 \cdot \pi \cdot 25

STEP 9

Multiplying 44 and 2525 gives us 100100, so the surface area of the sphere is: Areasphere=100π \text{Area}_{\text{sphere}} = 100 \cdot \pi

STEP 10

Let's compare our results.
The area of the circle is 100π100 \cdot \pi, and the surface area of the sphere is 100π100 \cdot \pi.
Are they the same?

STEP 11

Yes they are! 100π100 \cdot \pi is equal to 100π100 \cdot \pi.

STEP 12

The statement is **true**.
The area of the circle and the surface area of the sphere are both 100π100 \cdot \pi square units.

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