公制转换问题，为什么我的输出不准确？

Question

我试图理解为什么这段代码没有给我一个转换的准确答案

import math           # for access to pi
diameterLargeZa = 35  # in Europe, a large pizza is 35cm across
cm2in = 1/2.54      # conversion ratio from centimeters to inches
radiusLargeZa = diameterLargeZa / 2            # calculate radius from diameter
radiusLargeZa = radiusLargeZa / 10             # convert to cm from mm
radiusLargeZa = radiusLargeZa * cm2in          # convert to in from cm
euro_za2 = radiusLargeZa**2 * math.pi       # calculate area from diameter
print( euro_za2 )

Answer 1

抱歉，各位，无法添加评论，分数不够。 @Loocid半径是直径的两倍，而不是一半，是吗

答案是，如果你已经开始使用cm，为什么要将它转换为cm呢

import math           # for access to pi
diameterLargeZa = 35  # in Europe, a large pizza is 35cm across
cm2in = 1/2.54      # conversion ratio from centimeters to inches
radiusLargeZa = diameterLargeZa / 2            # calculate radius from diameter
# Line commented, not needed.
# radiusLargeZa = radiusLargeZa / 10             # convert to cm from mm, why ?
radiusLargeZa = radiusLargeZa * cm2in          # convert to in from cm
euro_za2 = radiusLargeZa**2 * math.pi       # calculate area from diameter
print( euro_za2 )

Answer 2

为什么要将毫米转换为厘米（第5行：这是从厘米到分米的转换）？。你已经有了以厘米为单位的半径。 您的代码应该如下所示：

import math           # for access to pi
diameterLargeZa = 35  # in Europe, a large pizza is 35cm across
cm2in = 1/2.54      # conversion ratio from centimeters to inches
radiusLargeZa = diameterLargeZa / 2            # calculate radius from diameter
# radiusLargeZa = radiusLargeZa / 10             convert to cm from mm (this is cm to decimetre, you already have value in cm)
radiusLargeZa = radiusLargeZa * cm2in          # convert to in from cm
euro_za2 = radiusLargeZa**2 * math.pi       # calculate area from diameter
print( euro_za2 )
# 149.12777453063953