The center of mass of a triangle that is made of a material which has a uniform mass is located at its centroid.
The centroid of a triangle is the point of intersection of its medians. It can be found by drawing straight lines from each vertex to the mid-point of the opposite side. These are called the medians.
The three medians of any triangle intersect at a common point which divides each of them in the ratio 2: 1
The center of mass of a triangle lies at its centroid which is the point of intersection of the medians.