Hot Air Balloon Lift
The hot air balloon is the oldest successful human-carrying flight technology. The first hot-air balloon flown in the United States was launched from the
Pressure (symbol: p or P) is the ratio of force to the area over which that force is distributed.
Pressure is force per unit area applied in a
Spherical Law of Cosines
In spherical trigonometry, the law of cosines (also called the cosine rule for sides) is a theorem relating the sides and angles of spherical triangles,
Length of an Arc of a Circle
Circular arc is a segment of a circle, or of its circumference (boundary) if the circle is considered to be a disc. Central angle is an angle whose apex