There are 5 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, 6)
Distance from target shape to cyan trapezoid at (1, 4): 2
Distance from target shape to brown square at (1, 8): 2
Distance from target shape to green square at (4, 6): 3
Distance from target shape to red square at (5, 8): 6
Closest shape is the cyan trapezoid at (1, 4) with distance 2</think>

<answer>(1, 4)</answer>