Answer
The statement does not make sense.
Work Step by Step
We have to solve this equation:
$\begin{align}
& d=-4\cos \left( \frac{\pi }{3} \right)\times 2 \\
& d=-4\cos \left( \frac{2\pi }{3} \right) \\
& d=-4\cos \left( \pi -\frac{\pi }{3} \right) \\
& d=4\cos \frac{\pi }{3} \\
\end{align}$
Put $\cos \frac{\pi }{3}=\frac{1}{2}$ ,
$\begin{align}
& d=4\times \frac{1}{2} \\
& d=2 \\
\end{align}$
Thus, to find the value, we do not have to solve the trigonometric equation; we can find the value of the trigonometric angle and simplify it arithmetically.
