There are 5 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 (3, 6)
Distance from target shape to pink rectangle at (2, 2): 5
Distance from target shape to yellow trapezoid at (4, 0): 7
Distance from target shape to green trapezoid at (1, 7): 3
Distance from target shape to brown right_triangle at (0, 6): 3
Closest shape is the green trapezoid at (1, 7) with distance 3</think>

<answer>(1, 7)</answer>