# Finding Outcrop Pattern from Outcrops / 3 point problem

On the below (rough) example, how would I go about finding the outcrop pattern? I'm aware of the following procedure:

1. Link highest and lowest outcrop to give strike line
2. Find the actual dip using theta=arctan(change_in_elevation_between_points_a_and_b/distance_between_points_a_and_b)
3. Find the distance along the strike line (1) at which the third outcrop (c) should rest, and link outcrop 3 (c) to that point
4. Extend the line from outcrop 3 behind the strike line until it can form a 90 degree angle with either outcrop a or outcrop b
5. find the distance represented by the line running at 90 degrees from the extended isoline (linking c and the strike line) to a / b.
6. Use theta=arctan(answer to_part_5/difference_in_elevation_between_c_and_outcrop_used_to_close_angle_in_5) to give the true dip
7. Add isolines parallel to the line created between outcrop c and a / b for each elevation (every 100m in the example I have sketched)
8. Mark where the isolines intersect topography heights of the same value
9. Join up each mark from step 8 (like a dot-to-dot) to give the outcrop pattern

However, I am confident in my outcrops as well as the dips that I collected in the field, yet the true dip that I get from the procedure above differs greatly from that collected in the field. Where am I going wrong? I am aware that the above procedure does not produce a completely accurate result, but I am concerned that the variation in dips means the outcrop patterns that I am creating using the steps described above are off.

I APPRECIATE THAT MY DIAGRAM SUGGESTS THAT TWO OF THE POINTS ARE AT THE SAME ELEVATION. PLEASE IGNORE THIS, AND ASSUME THEY ARE ALL NOTABLY DIFFERENT.