The grid lines will help you find an exact solution (assuming the two lines actually cross at a grid intersection point). However, the two lines may intersect somewhere off the grid lines which is when an estimation will be the next best thing.

First work with stencil one. use a combination of reflections, rotations, and translations to see whether stencil one will overlap with the original pattern. list the sequence of rigid transformations you used in your attempt, noting the type of transformation, the direction, the coordinates, and the displacement in