# from sympy import *
# def dasdasdasdas():
#
#
#
#     a = 12
#     b = Symbol('b')
#     c = Symbol('c')
#     d = Symbol('d')
#     ee = Symbol('ee')
#     rou = Symbol('rou')
#
#     theta = Symbol('theta')
#     rr = Symbol('rr')
#
#     solved_value = solve([cos(theta / 180 * pi) - (a / b), cos(rou / 180 * pi) - (c / d),
#                           cos(rr / 180 * pi) - (ee / c), a ** 2 + ee ** 2 - c ** 2,
#                           b ** 2 - a ** 2 - d ** 2 + c ** 2,
#                           b ** 2 + ee ** 2 - d ** 2], [b, c, d, ee, rou])
#     for i in solved_value:
#         print(i[-1])

# 180*acos(sqrt(1/(sin(pi*rr/180)**2 + cos(pi*rr/180)**2*cos(pi*theta/180)**2))*cos(pi*theta/180))/pi
# -180*acos(sqrt(1/(sin(pi*rr/180)**2 + cos(pi*rr/180)**2*cos(pi*theta/180)**2))*cos(pi*theta/180))/pi + 360
# 180*acos(-sqrt(1/(sin(pi*rr/180)**2 + cos(pi*rr/180)**2*cos(pi*theta/180)**2))*cos(pi*theta/180))/pi
# -180*acos(-sqrt(1/(sin(pi*rr/180)**2 + cos(pi*rr/180)**2*cos(pi*theta/180)**2))*cos(pi*theta/180))/pi + 360

if __name__ == '__main__':
    from math import *
    rr=45
    theta=40
    print(180*acos(sqrt(1/(sin(pi*rr/180)**2 + cos(pi*rr/180)**2*cos(pi*theta/180)**2))*cos(pi*theta/180))/pi)

30.682056176433413

rr是坡向角度减去火蔓延角度的那个角

theta是坡度