Question

an athletic facility is building an indoor track. the track is composed of a rectangle and two semicircles, as shown. a) write a formula fir the perimeter of the indoor track. b) solve the formula for x. c) the perimeter of the track is 660 feet, and r is 50 feet. find x. round your answer to the nearest foot.

Answer 1

Answer:

(a) P = 2x + 2r + 2πr

(b) x = ½(P - 2r - 2πr)

(c) x = 123 feet

Step-by-step explanation:

See Attachment for sketch of the track

Solving for (a): Perimeter of the track

This is calculated by adding the perimeter of the rectangle to the 2 semicircles as follows.

P = Perimeter of Rectangle + Perimeter of 2 Semicircles

P = 2(x + r) + 2 * πr

[Where r is the radius of both semicircles]

Open bracket

P = 2x + 2r + 2πr

Solving for (b): Formula for x

P = 2x + 2r + 2πr

Make x the subject of formula

2x = P - 2r - 2πr

Divide both sides by 2

x = ½(P - 2r - 2πr)

Solving for (c): the value of x when r = 50 and P = 660

Substitute the given values in the formula in (b) above

x = ½(P - 2r - 2πr)

x = ½(660 - 2 * 50 - 2π * 50)

x = ½(660 - 100 - 100π)

x = ½(560 - 100π)

Take π as 3.14

x = ½(560 - 100 * 3.14)

x = ½(560 - 314)

x = ½ * 246

x = 123 feet