Solution: The cosine of the angle between vectors $\mathbfa$ and $\mathbfb$ is given by $\cos\theta = \frac{\mathbfa \cdot \mathbfb}{\|\mathbfa\| \|\mathbfb\|}$. Compute the dot product: $\mathbfa \cdot \mathbfb = (1)(0) + (0)(1) + (1)(1) = 1$. The magnitudes are $\|\mathbfa\| = \sqrt1^2 + 0^2 + 1^2 = \sqrt2$ and $\|\mathbfb\| = \sqrt0^2 + 1^2 + 1^2 = \sqrt2$. Thus, $\cos\theta = \frac1{\sqrt2 \cdot \sqrt2} = \frac12$. The final answer is $\boxed{\dfrac12}$. - Tacotoon