Your job is to return the volume of a cup when given the diameter of the top, the diameter of the bottom and the height.

You know that there is a steady gradient from the top to the bottom.

You want to return the volume rounded to 2 decimal places.

Exmples:
```python
cup_volume(1, 1, 1)==0.79

cup_volume(10, 8, 10)==638.79

cup_volume(1000, 1000, 1000)==785398163.4

cup_volume(13.123, 123.12, 1)==4436.57

cup_volume(5, 12, 31)==1858.51
```

You will only be passed positive numbers.

Difficulty: EASY
Starter code: def cup_volume(d1, d2, height):
	

Solutions:
from math import pi

def cup_volume(d1, d2, h):
	return round(h / 12.0 * pi * (d1 ** 2 + d1 * d2 + d2 ** 2), 2)


from math import pi

def cup_volume(d1, d2, height):
	(r1, r2) = (d1 / 2.0, d2 / 2.0)
	return round(pi * height * (pow(r1, 2) + r1 * r2 + pow(r2, 2)) / 3.0, 2)


def cup_volume(d1, d2, h):
	return round(h * (d1 * d1 + d1 * d2 + d2 * d2) * 0.2617993878, 2)


cup_volume = lambda d, D, h: round(__import__('math').pi * h / 12 * (d * d + d * D + D * D), 2)


import math

def cup_volume(d1, d2, height):
	if d1 > d2:
		(d1, d2) = (d2, d1)
	if d1 == d2:
		return round((d1 / 2.0) ** 2 * math.pi * height, 2)
	x = d1 * float(height) / (d2 - d1)
	vol = (d2 / 2.0) ** 2 * math.pi * (height + x) / 3.0 - (d1 / 2.0) ** 2 * math.pi * x / 3.0
	return round(vol, 2)


def cup_volume(d1, d2, height):
	v = 3.14159265359 / 3 * height * ((d1 / 2) ** 2 + (d2 / 2) ** 2 + d1 / 2 * d2 / 2)
	return round(v, 2)


import math

def cup_volume(d1, d2, height):
	return round(math.pi * height * (d1 ** 2 + d2 ** 2 + d1 * d2) / 12, 2)


from math import pi

def cup_volume(d1, d2, h):
	(r1, r2) = (d1 / 2, d2 / 2)
	return round(pi * (1 / 3) * h * (r1 ** 2 + r2 ** 2 + r1 * r2), 2)