Question

1. What is the area of a circle with a a diameter of 20 cm in terms of pi?

2. What is the area of a circle with a radius of a 8 yd using 3.14 as pi?

3. The area of a circle in terms of pi is 49pi. What is the radius of the circle?

Help needed and it would be appreciated

Answer 1

1. 100pi cm

2. 200.96 yd

3. 7

Explanation:

1.) diameter = radius multiple by two (D = r × 2)

&

radius = diameter divided by two (r = D ÷ 2)

So

20 ÷ 2 = 10 => A = pi (10)power 2 => A = 100pi

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2.) 3.14 × (8)power2 =200.96

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3.) A = 49pi => 49pi = pi(r)power2

[ cross out the pi from both sides]

And your left with

49 = (r)power2

[square root both sides to get rid of the power]

And your left with

7 = r