Answer:

Step-by-step explanation:
Multiply numerator and denominator by √2

The perimeter of a Pentagon is all the length of the sides added up
A pentagon is a five sided shape
so...
900+900+900+900+900
or 900*5
That is 4500.
The perimeter of the Pentagon Building in Washington DC, whose side is 900 feet long, is 4500 feet around.
Hope this helps :)
Answer:
8
Step-by-step explanation:
The desired number is the difference between the number of messages sent by the 16th day and the number sent by the 9th day:
... n = t(16) - t(9)
... n = (40×√16) - (40×√9)
... n = 40×(4 - 3) = 40
40 text messages were sent between the ninth and sixteenth day of the month.