## Trigonometry (11th Edition) Clone

$[2cis(\frac{5\pi}{9})]^2$ = $-3.7588 - 1.3681i$ (Using calculator and corr. to 4 decimal places)
$[2cis(\frac{5\pi}{9})]^2$ = $2^2 cis(\frac{5\pi}{9}) cis(\frac{5\pi}{9})$ = $4 cis(\frac{5\pi}{9} + \frac{5\pi}{9})$ (Product Theorem) = $4 cis(\frac{10\pi}{9})$ = $-3.7588 - 1.3681i$ (Using calculator and corr. to 4 decimal places)