I would expect you to do better than that if I were your teacher. Are you familiar with polar coordinate representation of complex numbers (e.g., https://en.wikipedia.org/wiki/Complex_number#Polar_complex_plane) ?
This looks like a typo: cos(t/35) + isin(t/35) -- should not it be cos(35t)+i*sin(35t) ?Can you explain why the minus appeared outside?
Hint: eit = cos(t) + i sin(t) and [cos(t) + isin(t)]35 = cos(t/35) + isin(t/35)
You need to find t such that cos(t) = 1/2 and cos(t) = sqrt(3)/2
With all this type of question we first need the argument.