redetermine vs ascertain

redetermine and ascertain both are verbs.

Word	Noun	Adjective	Verb	Adverb
redetermine	No	No	Yes	No
ascertain	No	No	Yes	No

As verbs, ascertain is a hypernym of redetermine; that is, ascertain is a word with a broader meaning than redetermine:

redetermine: fix, find, or establish again
ascertain: establish after a calculation, investigation, experiment, survey, or study

Other hypernyms of redetermine include determine, find, find out.

redetermine (verb)	ascertain (verb)
fix, find, or establish again	be careful or certain to do something; make certain of something
	learn or discover with certainty
	find out, learn, or determine with certainty, usually by making an inquiry or other effort
	establish after a calculation, investigation, experiment, survey, or study