What is the average height of a high school kid

What is the area of triangle abc if a = 8, b = 11, and c = 15?

What is the solution to the equation? k/6.4=8.7 2.3 5.568 15.1 55.68

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.