Ineed in b and c and how do i put it in the model

Which is the equation of an ellipse with directrices at x = ±4 and foci at (2, 0) and (−2, 0)?

According to modern science, earth is about 4.5 billion years old and written human history extends back about 10,000 years. suppose the entire history of earth is represented with a 10-meter-long timeline, with the birth of earth on one end and today at the other end.

Select the lengths in centimeters that would form a right triangle