Manual of Land Surveying - With Tables #225805

In a triangle having sides each one mile in length, the difference in area, whether it be regarded as a plane triangle, or a triangle having sides curved with the earth's surface, is only 2} square feet. Each of the angles of such a spherical triangle would only exceed that Of the plane triangle by o.0019. And the angles Of a spherical triangle, whose area is square miles, would only exceed those of the plane triangle, having sides of the same length, by I.