Answer:
length = [9/2 + (9/2)sqrt(5)] cm
length = 14.56 cm
Step-by-step explanation:
In a golden rectangle, the width is a and the length is a + b.
The proportion of the lengths of the sides is:
(a + b)/a = a/b
Here, the width is 9 cm, so we have a = 9 cm.
(9 + b)/9 = 9/b
(9 + b)b = 81
b^2 + 9b - 81 = 0
b = (-9 +/- sqrt(9^2 - 4(1)(-81))/(2*1)
b = (-9 +/- sqrt(81 + 324)/2
b = (-9 +/- sqrt(405)/2
b = -9/2 +/- 9sqrt(5)/2
Length = a + b = 9 - 9/2 +/- 9sqrt(5)/2
Length = a + b = 9/2 +/- 9sqrt(5)/2
Since the length of a side of a rectangle cannot be negative, we discard the negative answer.
length = [9/2 + (9/2)sqrt(5)] cm
length = 14.56 cm
