Please help me out here

An equation where variables are used to represent known values—function notation true or false

You're locked out of your house. the only open window is on the second floor, 25 feet above the ground. there are bushes along the edge of the house, so you will need to place the ladder 10 feet from the house. what length ladder do you need to reach the window?

What is the point of inflection for the function f(x)=2cos4x on the interval (0, pi/2)