Answer:
<h2>20 cm.</h2>
Step-by-step explanation:
We know that the permiter is defined as
Where 
is the longest side, 
is the smallest and 
is the middle side.
If 
then, 
, where we need to find an expression for using the law of cosines.
Replacing all expression, the perimeter is
Using a calculator, the perimeter is 20 units centimeters.
The answer is about 12.5 (when rounded to the nearest 10th).
This can be found using the distance formula between each point. One distance is 5, one is
and one is
. Added together gives you the answer above.
Let p and w represent the speed of the plane and the speed of the wind, respectively.
.. speed = distance/time
.. p +w = 720/3 = 240
.. p -w = 720/4 = 180
Add the two equations to eliminate w.
.. 2p = 420
.. p = 210
.. w = p -180 = 30
The speed of the wind is 30 mph.
The speed of the plane in still air is 210 mph.
