There are 6 shapes on a 8x8 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 (5, 5)
Distance from target shape to brown square at (1, 2): 7
Distance from target shape to orange square at (1, 7): 6
Distance from target shape to yellow right_triangle at (7, 6): 3
Distance from target shape to gray square at (4, 2): 4
Distance from target shape to pink rectangle at (1, 4): 5
Closest shape is the yellow right_triangle at (7, 6) with distance 3</think>

<answer>(7, 6)</answer>