Spherical geometry other geometric concepts are defined as in plane geometry, but with straight lines replaced by great circles. Thus, in spherical geometry, angles are defined between great circles, resulting in a spherical trigonometry that differs from ordinary trigonometry in many respects; for example, the sum of the interior angles of a triangle exceeds 180 degrees. Spherical geometry is "not" elliptic geometry, but is rather a "subset" of elliptic geometry. For example, it shares with that geometry the property that a line has no parallels through a given point. Contrast this with Euclidean geometry, in which a line has one parallel through
OMB Circular A-21 OMB Circular A-21 OMB Circular A-21 is a Government circular that sets forth the rules governing the eligibility and calculation of costs in support of sponsored research, development, training and other works produced in agreement with the United States Federal Government, but does not attempt to identify or dictate agency or institutional participation in those works. The last revision is dated May 10, 2004. This circular is divided into ten sections: This section outlines the principles and policies that must be followed regarding the accounting principles, arrangements, and exemptions for any training or work produced under the contract as agreed