At `45^@` to magnetic meridian, the apparent dip is `30^@`. What is the true value of dip?

Answer

`tan^(-1)1sqrt6`

Explanation

Here, `theta=45^@, delta^'=30^@, delta=?`
From `tan delta^'=(tan delta)/(cos theta)`
`tan delta=tan delta^'`, `cos theta`
`=tan 30^@xxcos 45^@`
`=1/sqrt3xx1/sqrt2=1/sqrt6`
`delta=tan^-1(1//sqrt6)]`