接上一节的习题2，给出代码的另一种写法：
def triangle(a,b):
return 'The right triangle third side\'s length is {}'.format(pow((pow(a,2) + pow(b,2)),0.5))
print(triangle(3,4))运行结果为：
The right triangle third side's length is 5.0
Process finished with exit code 0与第一种代码的执行结果相同。
函数的参数传递包括两种：位置参数传递和关键词参数传递。
def trapezoid_area(base_up = 1, base_down = 2, height = 3):
return 1/2 * (base_up + base_down) * height
print(trapezoid_area())
print(trapezoid_area(4,5,6))
print(trapezoid_area(height = 3,base_down = 2,base_up = 1))运行结果是：
4.5
27.0
4.5