Two vectors u,v are orthonormal if and only if?

Both u,v are orthogonal and unit vectors

u,v are orthogonal

u,v are unit vectors

None of these

Orthonormal vectors satisfy two conditions: they are orthogonal ( $u cdot v = 0$ ) and unit vectors ( $||u|| = 1$ and $||v|| = 1$ .

This means they are perpendicular and have a magnitude of 1.