Find the exact circumference of a circle with the diameter equal to 8 ft

Pls i’m too dumb to know what i’m doing right now

How do you do this geometry problem

In two or more complete sentences, formulate how to use technology to calculate the appropriate regression model for the given data. you are not required to find the model, just choose the appropriate regression and explain how to use the technology. (-5,,2.,0.8), (0,-0.5), (2,-1.3), (3,-0.8), (5,2)