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Find the surface area . grapefruit with the circumfrace of 14

1 Answer

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Let's use 3.14 as pi.
So, since you've been given the circumference already, finding the radius is easy. You use the formula C = 2 x pi x R.
To find the radius, work backwards:
14/2=7
7/3.14=about 2.23, or 2.2 inches. That answer is your radius.
The formula for the surface area of a sphere is
4 x pi x R² . Now, since we know the radius, all we have to do is plug that into the formula, replacing "R" with our radius.
Our new formula:
4 x pi x 2.2
²
To solve this, we follow the rules of PEMDAS (parentheses, exponents, multiplication, division, addition, subtraction). Since there are no parentheses, we move on to the exponent, which is 2.2², which equals 4.84.
Our new formula:
4 x pi x 4.84
Let's plug in 3.14 as pi.
4 x 3.14 x 4.84
Now, from left to right:
12.56 x 4.84
= 60.7904, or about 60.79, or estimated further to 60.8.

Hope this helps!
User Adam Sitnik
by
7.8k points
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