A word that means three sided?

The function models the number of accidents

The population of a small rural town in the year 2006 was 2,459. the population can be modeled by the function below, where f(x residents and t is the number of years elapsed since 2006. f(t) = 2,459(0.92)

Aregular pan has a length that is 4/3 the width. the total area of the pan is 432in.2. what is the width of the cake pan?