Can anyone help me with this quickly?

How do you use the elimination method for this question? explain, because i really want to understand!

Meghan has created a diagram of her city with her house, school, store, and gym identified. a. how far is it from the gym to the store? b. meghan also wants to walk to get some exercise, rather than going to the gym. she decides to walk along arc ab. how far will she walk? round to 3 decimal places.

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