Let $T \in \mathsf{Exp}(\theta)$ be an D214: Exponential random positive real number.
Let $t \in \mathbb{R}$ be a D993: Real number.
Let $t \in \mathbb{R}$ be a D993: Real number.
Then
\begin{equation}
\mathbb{P}(T \leq t) =
\begin{cases}
1 - e^{- t \theta}, \quad & t \geq 0 \\
0, \quad & t < 0
\end{cases}
\end{equation}