The perimeter of the entire rectangle is 12 cm.
To do these problems, plug in a couple of values into the equations, and see the general shape of the graph. To ensure you were right, check them on an online graphing calculator. I highly recommend Desmos Graphing Calculator. Cheers!
$12.98 each. You would do $56.07 - $4.15. Then divide the answer of that by four.
15) factor out cos: cos(x)(sin(x)+1)=0
Now this is true when either cos(x)=0 (x=pi/2 and 3pi/2)
Or when sin(x)=-1 (x=3pi/2)
So it's solutions are pi/2 and 3pi/2