How can I rotate a triangle around its center?

I’m having trouble getting an isosceles triangle to orient itself to a vector that is aligned with an axis. It doesn’t matter which axis it’s normal faces, and it doesn’t matter which perpendicular axis the up vertex faces. I need it to be flat to one and point along another. Currently when I use

FRotationMatrix orientationRot = FRotationMatrix(cellRotation);
FVector changedVec = orientationRot.TransformVector(tempVerts[i].cellCornerToFVec());

The triangle only swivels around the world center. I imagined this rotating the triangle from it’s center toward the given rotation vectors. How would I go about doing that? As a bonus! I would like to transform this triangles location to be dead center of the world (after it is rotated).

Thanks in advance!

I tried getting the middle of the triangle (M) , then subtracting P[0] from M, then P[1] from M, and finally P[2] from M. I figured this would moved the triangle to the center. Then getting the rotation needed to face an axis, this did not work.