Yes, the corollary to one theorem can be used to prove another theorem.
Segment bisector
sss
The SAS theorem is used to prove that two triangles are congruent. If the triangles have a side-angle-side that are congruent (it must be in that order), then the two triangles can be proved congruent. Using this theorem can in the future help prove corresponding parts are congruent among other things.
Gram crackers
Yes, the corollary to one theorem can be used to prove another theorem.
segment bisector
Segment bisector
Proposition 3 of Book IV in Euclid's Elements (angle bisector theorem)
ASA
SAS
AAS (apex)
SAS
sss
Maybe, but a straight edge and a pair of compasses would have probably been used to construct a perpendicular line bisector for a given line segment.
Well, this will depend on the length of the sides of the triangle for what postulate or theorem you will be using.
(cos0 + i sin0) m = (cosm0 + i sinm0)