Question

if you are building a triad whose root is located on a line on the staff, where will the third and the fifth be located

Answer 1

If you are building a triad whose root is located on a line on the staff, where will the third and the fifth be located?

Answer: There are three triad positions that I am aware of. The first one is Triad Inversion and it occurs when the root is not the lowest-sounding pitch. The second one is First Inversion and it occurs when the third triad is the lowest-sounding pitch regardless of the arrangement of pitches. The final one is Second Inversion and it occurs when the fifth of the triad is the lowest-sounding pitch regardless of the arrangement of pitches.

I hope it helps, Regards.

Answer 2

If you are building a triad whose root is located on the staff then identify the
root, quality and bass note. The root and quality will tell three classes and If the quality is augmented, there is a major third above the root  and an augmented fifth above the root.
Hope it helps.