#1.34# radians is around #77^circ#, comfortably in the first quadrant.
#theta = 1.34 # is thus a ray from the origin into the first quadrant. It's not the line through the angle, because the part of the line in the third quadrant satisfies #theta = 1.34 + pi.#
So, understanding #x>0, y>0# we take tangents and get
# tan theta = tan(1.34)#
Since
#x = r cos theta #
# y = r sin theta #
we get
#tan theta = y/x#
and our equation becomes
#y/x = tan(1.34)#
#y = x tan(1.34) quad # for #x > 0.#
That's the ray through the origin and the first quadrant with slope #tan(1.34).# We explicitly exclude #x=0# which doesn't have the required angle.
