Math Is Fun Forum
Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °
You are not logged in.
- Topics: Active | Unanswered
#1 2008-02-15 01:35:56
- Melllyy
- Guest
Circles
Show using algerbra that if you double the radius of a circle, you will be doubling the circumference and quadrupling the area of the circle
#2 2008-02-15 01:46:04
- Daniel123
- Member
- Registered: 2007-05-23
- Posts: 663
Re: Circles
Let r be the length of the radius
C = 2πr
If you double the radius to 2r
C = 2π x 2r
= 4πr
= 2 x 2πr
Area = πr²
If you double the radius to 2r
Area = π(2r)²
= 4πr²
= 4 x πr²
Offline