# Three Coplanar Bisectors in Unit Sphere Construction

Three Coplanar Bisectors in Unit Sphere Construction

Draw a spherical triangle on the surface of the unit sphere centered at . Let be the point opposite on . Let the sides opposite the corresponding vertices be the arcs , , . Then the bisectors of , and (the supplementary angle of ) lie in the same plane.

ABC

S

O=(0,0,0)

B'

B

S

a

b

c

a

b

c

supp

c