The lines joining the places of the same horizontal intensity are known as

Lines joining the places of equal horizontal intensity are called

Lines joining the places of equal Dip are called

Lines joining the places of zero Dip' is called

Lines joining the places of zero declination is called

At two ends of a horizontal line, angles of equal size are drawn, and two points on the slanted lines are joined. Prove that the parts of the horizontal line and parts of slanted lines are in the same ratio.