ladder calculator

parallel side a:
parallel side b:
angle (θ):
angle (φ):
high (h):
area:
perimeter:
side c:
side d:
diagonal l1H2：
diagonal h1L2：

trapezoidal formula
1. area = h(a+b)/2

2. perimeter = a + b + c + d

3. diagonal l1H2 = sqrt(h2+(b-sqrt(c2-h2))2)

4. diagonal h1L2 = sqrt(h2+(b-sqrt(d2-h2))2)