area_square = lambda side : side * side
area_rectangle = lambda length,width : length * width
area_triangle =  lambda s,a,b,c : (s*(s-a)*(s-b)*(s-c)) ** 0.5

a=10
b=20
c=15
s = (a + b + c) / 2

print(area_square(a))
print(area_rectangle(a,b))
print(area_triangle(s,a,b,c))