A straight tunnel is to be driven between stations P and S which are on opposite sides of a hillside. Stations
Q and R were located such that P can be seen from Q and S can be seen from R with Q and. S being intervisible. The following observations were made:
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Clockwise horizontal angles
PQR = 78°14'26
QRS = 81°16'45"
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Horizontal distances (rn) AQ = 126.59
QR = 915.
RS = 109.32
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The coordinate of P are 1716.32 E, 6897.14 N and bearing PQ is 17218'39". Calculate:
a. The clockwise horizontal angle to be set off at P from PQ to the centre line of the tunnel
b. The clockwise horizontal angle to be set of at S from SR to the centre line of the tunnel
c. Horizontal length of the tunnel if P is located a horizontal distance of 45.19 m from one end of the tunnel and S is located a horizontal distance of 87.44 m from the other end. The tunnel falls within the line PS.