Question 257782
This is my problem : -2R+4U
I need to convert it into "polar form " 
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I am going to assume your number is -2 + 4i in complex number form.
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Conversion Rule:
When the rectangular form is a+bi
the polar form is:
r = sqrt(a^2+b^2)
theta = arctan(b/a) in its proper quadrant.
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Your Problem:
a = -2 ; b = 4
So, r = sqrt[(-2)^2 + 4^2] = sqrt(4+16) = 2sqrt(5)
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theta = arctan(4/-2) in the 2nd quadrant because (-2,4) is in the 2nd quadrant.
theta = -63.43+180 = 116.57 degrees
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Cheers,
Stan H.