Answer:
one side = 
Step-by-step explanation:
if you draw an octagon on a piece of paper, you can draw a square around it, you should be able to see a diagram of this attached, ignore the 6.
Let's say TP = a
since it's a regular octagon, TP = HT
and using the Pythagoras Theorem, we know a² + b² = c² and thus:
√(AT² + HA²) = HT
and since AT = HA which we will call x, the equation becomes:
√(2x²) = HT = a
rearrange the equation to solve for x and you get:
2x² = a²
x² = 
x =
which, if you rationalise the denominator, you get:
x = 
A = P + I
2a = a + PTR/100
2a = a + 5aT/100
2a = a(1+T/20)
2=1+T/20
T=20 yrs
Answer: y = 25x + 50
Explanation: the total cost if the rental is a linear function of the number of days of the rental (x). Each day costs $25, so that is the slope of the line. Since there is also a one-time fee, independent of the number of days, this amount $50 represents a vertical shift of the line on the graph, by 50. y=25x+50 is an algebraic expression of that.