The teacher will be very surprised to see your correct solution 😉
log(y + 1) = c - log(cos(x))
/ / c \\ / / c \\
| | e || | | e ||
x1 = - re|acos|-----|| + 2*pi - I*im|acos|-----||
\ \1 + y// \ \1 + y//
/ / c \\ / / c \\
| | e || | | e ||
x2 = I*im|acos|-----|| + re|acos|-----||
\ \1 + y// \ \1 + y//
x2 = re(acos(exp(c)/(y + 1))) + i*im(acos(exp(c)/(y + 1)))
sum
/ / c \\ / / c \\ / / c \\ / / c \\
| | e || | | e || | | e || | | e ||
- re|acos|-----|| + 2*pi - I*im|acos|-----|| + I*im|acos|-----|| + re|acos|-----||
\ \1 + y// \ \1 + y// \ \1 + y// \ \1 + y//
=
2*pi
product
/ / / c \\ / / c \\\ / / / c \\ / / c \\\ | | | e || | | e ||| | | | e || | | e ||| |- re|acos|-----|| + 2*pi - I*im|acos|-----|||*|I*im|acos|-----|| + re|acos|-----||| \ \ \1 + y// \ \1 + y/// \ \ \1 + y// \ \1 + y///
=
/ / / c \\ / / c \\\ / / / c \\ / / c \\\ | | | e || | | e ||| | | | e || | | e ||| -|I*im|acos|-----|| + re|acos|-----|||*|-2*pi + I*im|acos|-----|| + re|acos|-----||| \ \ \1 + y// \ \1 + y/// \ \ \1 + y// \ \1 + y///
-(i*im(acos(exp(c)/(1 + y))) + re(acos(exp(c)/(1 + y))))*(-2*pi + i*im(acos(exp(c)/(1 + y))) + re(acos(exp(c)/(1 + y))))