Answer:


Step-by-step explanation:
Given
A circular ring
Required
The length
Let
the radius of the ring
The length is calculated by calculating the circumference of the ring.
This is calculated using:

or

Where
diameter
and 
I think the next one is,65.0
Answer: The girl herself ran faster than her friend.
Step-by-step explanation:
This answer, of course assumes a lot of variables, but for the sake of keeping things simple, lets assume the following, the people are ran in a "straight line" with no "obstacles" in their way, and ran on the same track.
Calculating in meters-per-second for the girl who ran 200 meters in 28 seconds, you get 7.14285714286 meters per second
Calculating in meters-per-second for the girl who ran 400 meters in 60 seconds, you get 6.66666666667 meters per second
Comparing the two results, it can be "accurately" concluded that the girl herself ran faster than her friend under the following assumptions earlier stated.
5 give Brainly then I’ll help with all the other ones
Answer:
x=-5, x=9
Step-by-step explanation:
we know that
The formula to solve a quadratic equation of the form
is equal to
in this problem we have
equate to zero
so
substitute in the formula
therefore
The solutions are x=-5, x=9