The plane of dip circle is set in the geographic meridian and the apparent dip is `theta_(1)`. It is then set in a vertical plane perpendicular to the geographic meridian. Now, the apparent dip is `theta_(2)`. The angle of declination `theta` at that place is

Options

A. `theta =tan^(-1)( tan delta_(1)tan delta_(2))`
B. `theta =tan^(-1)( tan delta_(1) +tan delta_(2))`
C. `theta =tan^(-1)""( tan delta_(1) )/(tan delta_(2))`
D. `theta =tan^(-1)( tan delta_(1) - tan delta_(2))`

Answer

C

Explanation

Here , ` tan delta_(1)=(V)/( H cos theta )`

`tan delta_(2)=(V)/( H cos (90^(@)-theta ))=(V)/( H sin theta )`
`( tan delta_(1))/( tan delta_(2))=( sin theta )/( cos theta )=tan theta `
`or theta =tan^(-1)""((tan delta_(1))/( tan delta_(2)))`