Answer
$$\lim_{t\to0}G(t)=0.5$$
Work Step by Step
$$G(t)=\frac{1-\cos t}{t^2}$$
(a) The table is shown below.
As we can see from 2 tables below, as $t$ gets more decimals and approaches $0$, the value of $G(t)$ also gets more decimals and apparently approaches $0.5$. So I would estimate here that $\lim_{t\to0}G(t)=0.5$.
(b) The graph is shown below.
Again, looking at the graph, the closer $t$ approaches $0$, the closer $G(t)$ gets to $0.5$.
