The values of the apparent angles of dip in two planes at right angles to each other are 30o and 45o. Then the true value of the angle of dip at the place is

tan30o=tanδcosθ= or cosθ=tanδtan30o=3tanδAgain, tan45o=tanδsinθ= or sinθ=tanδNow, sin2θ+cos2θ=1∴tan2δ+3 tan2δ=1or tan2δ=14 or tanδ=12\or 1cot δ=12 or δ=cot-12