Hi Talia!
First, you will need the area formula of a triangle to resolve this exercise, which is :

As you can see, you will have to find the measure of the base of the triangle, which is the segment BC, and the measure of the height of the triangle, which is the segment AH.
Since you already have the coordinates of each point, the fastest way to resolve this problem would be to find the distance between the point A and the point H, the measure of the height, and between the point B and the point C, the base. In order to do that, you will need this formula :

Once you find the two distances, the last step would be to insert them in the area formula to get a final answer.
Let us know if you have any other question! :)