Can someone please help me I don’t get this (Due today)

The blue segment below is a diameter of o. what is the length of the radius of the circle?

An object is accelerating at a constant rate. its velocity in feet per second as a function of time in seconds can be modeled by the linear function v(t) = 2.5t. what does the dependent variable represent for this function? a) acceleration b) distance c) slope d) velocity

I6.8.4 test lucas took out a car loan for $14,475 that has a 0% apr for the first 16 months and will be paid off with monthly payments over 5 years. for how many months will lucas be charged interest?