A dip circle shows an apparent dip of `60^@` at a place where the true dip is `45^@`. If the dip circle is rotated through `90^@`, what apparent dip will it show?

Explanation

If `delta_1 and delta)2` be the apparent dips shown by the dip circle in the two perpendicular positions, the true dip `delta` is given by
`cot^2 deta = cot^2 delta_1 + cot^2 delta_2`
or, `cot^2 45^@ = cot^2 60^@ + cot^2 delta_2`
or, `cot^@ delta_2 = 2/3`
or, `cot delta)2 = 0.816` giving `delta_2 = 51^@`.