Station 3 (Known) -
Station 1 (Target) -
Station 2 (Calculated) -
Sub-base (SUSHI) -

Mathematical Solution Breakdown

1 Solve Triangle S1-S2-Subbase (SUSHI)

Determine interior angles at Station 1 and Station 2 to find the distance between Station 2 and Station 1 ($D_{12}$).

Using the Sine Rule (Dragon Formula), compute the unknown side opposite to the Sub-base angle:

2 Solve Primary Triangle S1-S2-S3

Determine the interior angles of the larger triangle formed by the three stations ($\triangle(\text{S1-S2-S3})$) to calculate the distance between Station 3 and Station 1 ($D_{31}$).

Apply the Sine Rule to calculate the length of the unknown side $D_{31}$ opposite to the angle at Station 2:

3 Calculate Coordinates for Station 1

Compute grid deltas ($dE, dN$) from Station 3 to Station 1 using the solved distance and the given azimuth $A_{31}$.

Apply changes to the Easting and Northing of Station 3 to yield Station 1's coordinates: