Posted by Anonymous on Tuesday, August 7, 2012 at 5:09pm.
Given the rectangularform point (–1, 4), which of the following is an approximate primary
representation in polar form?
A. −(4.12, 1.82)
B. (−4.12, −1.33)
C. (4.12, 1.82)
D. (4.12, 4.96)
Change 8 cis 240degrees to rectangular form.
A. 4(Square root 3)4i
B. 8(Square root 3)8i
C. 44(Square root 3i)
D. 88(Square root 3i)

Trigonometry  Reiny, Tuesday, August 7, 2012 at 7:05pm
(1,4) is in quadrant II
tan^1 Ø = 4
Ø = 104° or 1.82 radians
the length of r is √(1+16) = √17 = appr 4.12
mmmmhhhh? Can you do something with that?
8 cis 240°
= 8(cos240° + isin240°)
= 8(1/2 + i(√3/2)
= 4  4√3 i