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January 30, 2015

January 30, 2015

Posted by **Drake** on Sunday, June 30, 2013 at 8:58am.

z=2(cos8∘+icos82∘).

Then z^5 can be expressed as r(sinα∘+icosα∘), where r is a real number and 0≤α≤90. What is the value of r+α?

- Trigonometry -
**Steve**, Sunday, June 30, 2013 at 5:57pmsince cos 82° = sin 8°,

z^5 = 2^5 cis(5*8)

= 32 cis 40°

= 32 (cos40° + i sin40°)

= 32 (sin50° + i cos50°)

32+50 = 82

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