The formula for the area, A, of a circle is A = πr2 , where r is the circle’s radius, and the formula for the circumference, C, of a circle is C = πd , where d is the circle’s diameter. Which statement is correct?

Respuesta :

The second statement is correct, the one with the circumference formula.

The first one , the one about the area of the circle, is wrong. The formula should actually look like this: [tex]A = \pi r^2[/tex]. It is the radius squared, not the radius times 2.


Answer:

The formula for the circumference, C, of a circle is C = πd , where d is the circle’s diameter.

Step-by-step explanation:

For a circulus with radius r, we have that:

The area of the circulus is:

[tex]A = \pi r^{2}[/tex]

That is, the radius is squared, not multiplied by 2, so the first statement is incorrect.

The circumference of the circulus is:

The derivative of the area, so

[tex]C = 2\pi r[/tex]

However

The radius if half the diameter. So

[tex]C = 2\pi \frac{d}{2}[/tex]

[tex]C = \pi d[/tex]

So the correct statement is:

The formula for the circumference, C, of a circle is C = πd , where d is the circle’s diameter.