Two identical triangles can be spliced into a graph: isosceles triangle, parallelogram, diamond, rectangle, square and ordinary quadrilateral. 1. Two identical obtuse triangles can be combined into a parallelogram, which meets the condition that the two groups of sides are parallel and equal respectively. 2. Two identical right triangles can be spliced into rectangles, parallelograms and isosceles triangles according to different splicing methods. 3. Two identical isosceles right-angled triangles can make a square, so the two waists of the isosceles right-angled triangle are equal, and the included angle is 90 degrees. 4. Two identical regular triangles can be combined into a diamond, that is, a special parallelogram. 5. Two identical acute triangles can be combined into a parallelogram.