Now AlC the area of AlC is going to be equal to one half base times height so this is going to be one half the basis of the length of AC one half AC times the height times this altitude right over here which is just going to be r times r that's the area of AlC and then the area of BlC is going to be one half the base which is BC times a height which is r and then plus the area of AlB this one right over here is going to be one half the base which is the length of the side AB