Whose work at the constitutional convention earned him the title "father of
the constitution"?

James Madison work at the Constitutional Convention earned him the title "Father of  the Constitution"

Explanation:

James Madison who was the fourth president of the United States who served in the office from the year 1809 to the year 1817 and is known fondly by the name of The father of the constitution.

This name was given to him because of the contributions that he had made in the field of making of the bill of rights and the drafting of the first ten amendments. His role in the field of ratification was also one of the major reasons he was given this name as the father of the constitution.

done

explanation:

6 units. ab and lo are congruent sides, and if ab= 6 units, then lo would be the same.