#3**+5 **

They are complex numbers, or rather standard abbreviations for complex numbers.

0.72\(\angle (-5\pi/36)\) is a complex number with modulus 0.72 and argument \(-5\pi/36\).

The rule for division, (deduce it by writing the numbers in their cos + i.sin form), is divide the moduli and subtract the arguments.

So, for example \(12\angle(\pi/4)/2\angle(\pi/6)=6\angle(\pi/12).\)

Guest Nov 2, 2015

#4

#5**+5 **

Put the numbers in their polar forms, \(r(\cos\theta+\imath\sin\theta)\), multiply top and bottom by the conjugate of the denominator and then, having multiplied out the brackets, use some standard trig identities to simplify.

I have to go out now, I'll get back to it later if it's still a problem.

Guest Nov 2, 2015

#8**+5 **

yeah he raised the e^i theta to the power of negative 1 to get it on the numerator but forgot to do the same to r2.

Guest Nov 7, 2015

edited by
Guest
Nov 7, 2015