to the sum from j=1 to 3 and k=1 to 3 of epsilon 1jk times a sub j times b sub k. The only two nonzero terms are epsilon 123 times a sub 2 times b sub 3 + epsilon 132 times a sub 3 times b sub 2. Since epsilon 123 is equal to one and epsilon 132 is equal to minus
The Remarkable Relationship between the Levi-Civita Symbol and the Kronecker Delta | Deep Dive Maths