a)Consider the complex number z1=-3+4i

i) Express this number as z1=re^iθ

ii) Find ln(z1)

SO WE KNOW WHAT r=5

AND WE KNOW THAT θ=126,... ?

here i have a problem - i dont know how to slove the a angle (this angle must be with PI) having the angle i know how to but to z1=re^iθ

I dont know how to solve ii) i found on wikipedia the rule but i dont understnd - can somebody help ?