There are 3 shapes on a 10x10 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, 9)
Distance from target shape to yellow rectangle at (9, 3): 14
Distance from target shape to gray square at (5, 5): 8
Closest shape is the gray square at (5, 5) with distance 8</think>

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