Please help me solve this :)

Can someone me do math because i am having a breakdown rn because i don’t get it

Which of the expressions (on the photo document i inserted) together represent all solutions to the following equation? 8cos(12x)+4=-4 *the answer should be in degrees.* > i would like for someone to explain the process to find the solutions for this.

Which expression is rational? 6. , square root two, square root 14, square root 49