Answer
Velocity vector $v(t)$ and acceleration vector $a(t)$ are orthogonal.
Work Step by Step
We are given that the particle is moving with constant speed.
This means that the tangential acceleration $a_T$ is zero.
Let $v(t)$ denote velocity vector and $a(t)$ show acceleration vector.
We have $a_T=\dfrac{v(t) \cdot v'(t)}{|v(t)|}$
If $a_T=0$
Then $v(t) \cdot v'(t)=0$
This means that $v(t)$ is perpendicular to $v'(t)$.
Hence,
Velocity vector $v(t)$ and acceleration vector $a(t)$ are orthogonal.
