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

Answer

`51^@`

Explanation

Here, `delta_1=60^@`, `delta=45^@`, `delta_2=?`
As `cot^2delta_1=cot^2delta_2=cot^2delta`
`:. cot^2delta_2=cot^2delta-cot^2delta_1`
`=(cot45^@)^2-(cot60^@)^2`
`=1-(1/sqrt3)^2=2/3=0*67`
`cot delta_2=sqrt(0*67)=0*816`
`:. delta_2=cot^-1(0*816)=51^@`