What is "Tikvas"?
Rashi: It is from the root "Kav" 1 (line) or rope.
Radak: It is a Kav (rope) twined from scarlet threads.
Radak citing Targum Yonasan: It is the edge of a scarlet garment. They said "ha'Zeh"
Why is there a Tzeirei under the Tav in "Horadtenu"? There should be a Chirik!
Radak: Sometimes they are interchanged, like Yaf'il and Yaf'el.