What is the multiplicative inverse of 1 7/12

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.

*segment an is an altitude of right ? abc with a right angle at a. if ab = 2root 5 in and nc = 1 in, find bn, an, ac.

What are the domain and range of the function below? a) domain: (-4,0) range: [-2,infinity) b) domain: (-3,0) range: [-2,infinity) c) domain: (-infinity,infinity) range: [-2, infinity) d) domain: [-2,infinity) range: (-infinity,infinity)