Ineed with starting this problem. i don't know how to find the area of a triangle with just the apothem.

Check the picture below

notice, that running a line from the center, you end up with an angle bisector to a vertex of the triangle, now, this is a "regular polygon", so, all sides are equal, for a triangle, when all sides are equal, all angles are also equal, and since the sum of all internal angles in a triangle must add up to 180°, then that means, each angle is 60°

now, you run an angle bisector through it, you end up with a 30°, 30° split, and that gives you a 30-60-90 triangle

Yes, that is the correct formula. to solve this problem given the number of years, plug in the number of years for t and plug the whole thing into the