Help me on #1 w/ b, c, and d!! Also show me the steps how did you got it. Please and thank you! (:

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.

What number gives you a irrational number when added to 2/5

For the following equations, find the ratio of a to b. be sure to show all of your work. a. 3a = 6b b. 15a = 5b