There are 4 shapes on a 9x9 grid. Which shape is closest to the purple right_triangle in terms of Manhattan distance? The final answer is the grid position of the closest shape like (row_index, column_index).
<think>Target shape: purple right_triangle at (1, 8)
Distance from target shape to orange right_triangle at (6, 5): 8
Distance from target shape to yellow square at (5, 1): 11
Distance from target shape to pink square at (8, 5): 10
Closest shape is the orange right_triangle at (6, 5) with distance 8</think>

<answer>(6, 5)</answer>