Salah satu bahan yang dibahas di ruang vektor adalah keortogonalan antara dua vektor. Konsep keortogonalan umumnya dikenal di ruang hasil kali dalam. Di ruang ber-norm terdapat konsep keortogonalan Pythagoras, sama kaki (Isosceles), dan Birkhoff James. Kemudian, Gahler memperkenalkan ruang ber-norm-2 dan ruang hasil kali dalam-2. Di tesis ini, dibahas konsep keortogonalan Pythagoras, sama kaki, dan Birkhoff James di ruang ber-norm-2 dan konsep keortogonalan-G di ruang hasil kali dalam-2. Kemudian, dibahas hubungan keekuivalenan antara konsep keortogonalan Pythagoras, sama kaki, dan Birkhoff James di ruang ber-norm-2.

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Orthogonality is one of the main topic in a vector space. Orthogonality of 2 vectors is generally known in inner product space. In normed space, there are Pythagorean, isosceles, and Birkhoff James orthogonality. Later, Gahler introduced a 2-normed space and a 2-inner product space. In this thesis, we discuss about Pythagorean, isosceles, and Birkhoff James orthogonality in a 2-normed space and G-orthogonality in a 2-inner product space. Then, we discuss the equivalency relations between Pythagorean, isosceles and Birkhoff James orthogonality in 2-normed space.