Question

Would appreciate some math help !!

Answer 1

Answer:

(D). $\frac{\sqrt{2} }{8}$ cis $\frac{47\pi }{36}$

Step-by-step explanation:

cis $\alpha$ × cis $\beta$ = cis ( $\alpha$ + $\beta$ )

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$\frac{\sqrt{6} }{6}$ cis $\frac{5\pi }{9}$ × $\frac{\sqrt{3} }{4}$ cis $\frac{3\pi }{4}$ = ( $\frac{\sqrt{6} }{6}$ × $\frac{\sqrt{3} }{4}$ )[cis ( $\frac{5\pi }{9}$ + $\frac{3\pi }{4}$ )] = $\frac{\sqrt{2} }{8}$ cis $\frac{47\pi }{36}$