Question

Does anyone know how to do 7a?

Answer 1

So if you check the picture below

the track is really just a rectangle with two semi-circles

now, you can just put together two semi-circles, and you'd end up with a full circle

the diameter of the circle is 22.8, thus the radius is half that, or 11.4

a)

length of the lap track is the circumference of the circle plus the two lengths of the rectangle

$\bf \textit{circumference of a circle}\\\\ C=2\pi r\qquad r=11.4\implies C=22.8\pi$

now, the rectangle has a length of 49.2, so one lap, one go-around will then be, 49.2+49.2+22.8π


b)

now, if she ran 625 meters, how many laps is that? well 625 divided by 49.2+49.2+22.8π, that many laps

c)

$\bf \textit{area of a circle}\\\\ A=\pi r^2\qquad r=11.4\implies A=11.4^2\pi \implies A=129.96\pi$

now, the area of the rectangle is just 22.8 * 49.2

the area of the field is just the sum of their areas