Ans: C
Add a straight line from the upper base to the lower base as shown below.
Add a straight line from the upper base to the lower base as shown below.
By Pythagoras Theorem, we have
$\begin{array}{rcl}
a^2 & = & 3^2 + 4^2 \\
a & = & 5
\end{array}$
Therefore, we have $\sin x = \dfrac{4}{5}$.
