Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

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**KaJohn****Guest**

I skipped geometry and moved to alg 2 from alg 1, long story. Anyway problem is:

The formula for the area A of a circle with diameter d is A=pi(d/2)squared. Write an expression to represent the area of the circle.

Also there is image of a circle to the right, i'm not sure if it's significant in any way, it shows circle, diameter line, dot in middle, and (y+5) over dot.

Can somebody please explain in detail how i understand/do these?

**ryos****Member**- Registered: 2005-08-04
- Posts: 394

I'm not sure I understand what the problem wants you to do. I'm guessing that they just want you to plug the diameter of the circle pictured into the formula they give you and write that down.

So, you need the diameter of the circle, but I have no idea what the (y+5) is supposed to represent.

Can you elaborate?

P.S.

That's an algebra II problem? Huh?

El que pega primero pega dos veces.

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**KaJohn****Guest**

That is exact way it's written in book, of course i can't write sq. root so iwrote it in words...please help me solve it

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,651

So, it's centre has something to do with (y+5) ... but they don't want the equation of the circle, they want the equation of the area ... hmmm ... maybe you are supposed to figure out the diameter from the diagram - is that possible?

(BTW: you can use the symbols at top. × ½ √ ∞ etc, just drag your mouse over one and copy and paste so you end up with A = π (d/2)² )

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**KaJohn****Guest**

that worked, thanks alot mathisfun, my dear friend <3

**ajp3****Member**- Registered: 2005-08-25
- Posts: 9

sounds like the answer's supposed to be:

A = pi (y+5)²/4 = (pi/4) (y² + 10y + 25)

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