help de-Abs me plz

spherical_triangle_snippet.py

from __future__ import print_function # still using Python 2.7
import sympy

print(sympy.__version__) # displays 1.1.1

# create some symbols for angles
p, q, r = sympy.symbols('p, q, r', real=True)

# create some symbols for unknown elements of lQ
x1, y1, z1 = sympy.symbols('x1, y1, z1')

# define vectors we know so far
P = sympy.Matrix([0, 0, 1])
lR = sympy.Matrix([1, 0, 0])
lQ = sympy.Matrix([x1, y1, z1])

lQ_equations = [
    sympy.Eq(lQ.dot(P), 0),              # lQ contains P
    sympy.Eq(lQ.dot(lR), -sympy.cos(p)), # angle at point P
    sympy.Eq(lQ.dot(lQ), 1)              # lQ is a unit vector
]

S = sympy.solve(lQ_equations, x1, y1, z1, dict=True, simplify=True)
print('found {} solutions for lQ:'.format(len(S)))
print('\n'.join([sympy.pretty(sln) for sln in S]))

lQ = lQ.subs(S[0])
print('now lQ is {}'.format(lQ))
# displays Matrix([[-cos(p)], [-Abs(sin(p))], [0]])