The needle of a dip circle shows an apparent dip of 450 in a particular position and 530 when the circle is rotated through 900. Find the true dip.
If δ1 and δ2 be the apparent dips shown by the dip circle in the 2 perpendicular positions, the true dip δ is given by
Cot2δ=Cot2δ1+Cot2δ2
⇒Cot2δ=Cot2450+Cot2530
Cot2δ = 1.56
Cot2δ = 1.56
δ=38.60≈390.