Answer:
6.5e^(i·(-157.38°)) ≈ 6.5e^(-2.7468i)
Explanation:
A suitable calculator can find the value of this ratio for you.
((2+3i)/(1-i))² = -6 -2.5i ≈ 6.5∠-157.38° ≈ 6.5e^(-2.7468i)
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The second attachments shows the calculator set to radian mode for the angle measure.