The pair of line represented by 〖ax〗^2+hxy+〖by〗^2= 0 will be orthogonal if.

The pair of line represented by 〖ax〗^2+hxy+〖by〗^2= 0 will be orthogonal if:

a + b = 0

a + b > 0

h2 - ab < 0

h2 - ab = 0