Having a bit of trouble with some complex numbers! I was able to do the first bit: Find the roots of z^4+1=0 and show them in an Argand diagram and resolve z^4 into real real quadratic factors.
But then got stuck on deduce that: cos2theta =2(costheta- cos pie/4) (cos theata-cos3pie/4)
If ya dont understand lol i got the question out of 4unit Patel Mathematics Complex Numers Exercise 4J! Q3
If ya dont understand lol i got the question out of 4unit Patel Mathematics Complex Numers Exercise 4J! Q3