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  2. Horizontal coordinate system - Wikipedia

    en.wikipedia.org/wiki/Horizontal_coordinate_system

    Azimuth is measured eastward from the north point (sometimes from the south point) of the horizon; altitude is the angle above the horizon. The horizontal coordinate system is a celestial coordinate system that uses the observer's local horizon as the fundamental plane to define two angles of a spherical coordinate system: altitude and azimuth.

  3. Geodetic coordinates - Wikipedia

    en.wikipedia.org/wiki/Geodetic_coordinates

    Geodetic latitude and geocentric latitude have different definitions. Geodetic latitude is defined as the angle between the equatorial plane and the surface normal at a point on the ellipsoid, whereas geocentric latitude is defined as the angle between the equatorial plane and a radial line connecting the centre of the ellipsoid to a point on the surface (see figure).

  4. Spherical coordinate system - Wikipedia

    en.wikipedia.org/wiki/Spherical_coordinate_system

    Even with these restrictions, if the polar angle (inclination) is 0° or 180°—elevation is −90° or +90°—then the azimuth angle is arbitrary; and if r is zero, both azimuth and polar angles are arbitrary. To define the coordinates as unique, the user can assert the convention that (in these cases) the arbitrary coordinates are set to zero.

  5. Grade (slope) - Wikipedia

    en.wikipedia.org/wiki/Grade_(slope)

    (This is the angle α opposite the "rise" side of a triangle with a right angle between vertical rise and horizontal run.) as a percentage , the formula for which is 100 × rise run {\displaystyle 100\times {\frac {\text{rise}}{\text{run}}}} which is equivalent to the tangent of the angle of inclination times 100.

  6. Solid angle - Wikipedia

    en.wikipedia.org/wiki/Solid_angle

    The external surface area A of the cap equals r2 only if solid angle of the cone is exactly 1 steradian. Hence, in this figure θ = A/2 and r = 1. The solid angle of a cone with its apex at the apex of the solid angle, and with apex angle 2 θ, is the area of a spherical cap on a unit sphere

  7. Altitude - Wikipedia

    en.wikipedia.org/wiki/Altitude

    Pressure altitude is the elevation above a standard datum air-pressure plane (typically, 1013.25 millibars or 29.92" Hg). Pressure altitude is used to indicate "flight level" which is the standard for altitude reporting in the U.S. in Class A airspace (above roughly 18,000 feet).

  8. Altitude (triangle) - Wikipedia

    en.wikipedia.org/wiki/Altitude_(triangle)

    Altitudes can be used in the computation of the area of a triangle: one-half of the product of an altitude's length and its base's length (symbol b) equals the triangle's area: A = h b /2. Thus, the longest altitude is perpendicular to the shortest side of the triangle.

  9. Solar zenith angle - Wikipedia

    en.wikipedia.org/wiki/Solar_zenith_angle

    It is the complement to the solar altitude or solar elevation, which is the altitude angle or elevation angle between the sun’s rays and a horizontal plane. [1] [2] At solar noon, the zenith angle is at a minimum and is equal to latitude minus solar declination angle. This is the basis by which ancient mariners navigated the oceans. [3]