Oh, nevermind, I found my mistake.
Hey, how did you find that the radius is 4?
I understand that you got it but just looking and run numbers in the head probably, but how can I get it mathematically, this is the part where I felt.
GreenlightTestPrep wrote:
Carcass wrote:
If the perimeter of a semi-circle is 4π + 8, what is the area of the semi-circle?
A. 16π
B. 8π
C. 4π
D. 8
E. 4
Let r = the RADIUS of the circle
So, the length of the diameter =
2rThe circumference of an ENTIRE circle = 2πr
So, the circumference of a SEMIcircle = 2πr/2 =
πrWe get:
So the PERIMETER =
πr +
2rWe're told that the PERIMETER = 4π + 8
We can write:
πr +
2r =
4π +
8We can see that, if r = 4, the equation holds true
So, the radius must be
4What is the area of the semi-circle?Area of circle = πr²
So, area of SEMIcircle = πr²/2
So, the area of the given circle = π(
4²)/2
= 16π/2
= 8π
Answer: B
Cheers,
Brent