At a point A on the earth's surface of angle of dip, `delta=+25^(@)`. At a point B on the earth's surface the angle of dip, `delta=-25^(@)`. We can interpret that.

At a point A on the earth's surface the angle of dip delta = +25^(@) . At a point B on the earth's surface the angle of dip, delta = -25^(@) . We can interpret that :

Where on the earth's surface , the value of angle of dip is 90^(@) ?

Where on the earth.s surface is the magnetic dip zero ?