Question

Area of a circular ring: A = 4
`\pi`pw

Solve for p. Find p when A = 22 cm^2 and w = 2 cm

Perimeter of a track: P = 2
`\pi`r + 2x
Solve for r. Finf r when P = 440 yrds and x = 110 yrds

Answer 1

1a) A = 4πpw
/4πw = /4πw
A / 4πw = p

1b) A = 4πpw
22 = 4πp(2)
p = 11/4π (≈0.87)

2a) P = 2πr + 2x
P - 2x = 2πr
/2π /2π
P-2x / 2π = r

2b) P = 2πr + 2x
440 = 2πr + 2(110)
r = 110/π (≈35.014)