Number 180

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[EECS]  180(W, KW or MW) is one of standard numerical values for resistors (of tolerance class 5%). 180pF (picofarads) is one of standard numerical values for capacitors.

[Game]  The number of white pieces in the Go game; versus 181 black pieces. Go is called Weichi in China and Baduk in Korea.

[Geology]  The 180o East or West meridian (longitude line) designated as the International Date Line in the Pacific Ocean, but the Line intentionally wanders around countries, states or islands in order not to divide them into different time zones, as do the time zones’ boundary lines.

[Math.]  A half revolution, a straight angle (or a semicircle) is 180o = p radians = 200 grads (grades). (Units for angle measurements).

[Math.]  sin(270o) = cos(180o) = tan(135o) = –1.

sin(0o) = sin(180o) = cos(90o) = cos(270o) = tan(0o) = tan(180o) = cot(90o) = cot(270o) = sinh(0) = tanh(0) = log(1) = 0.

[Math.]  Sum of 2 supplementary angles is 180o: sin(a) = sin(180oa).

[Math.]  tan(a) = tan(180o+a).

[Math.]  Interesting formula: arctan1+arctan2+arctan3 = 180o.

[Math.] An obtuse angle is greater than 90o, but less than 180o.

A reflex angle is greater than 180o but less than 360o.

[Math.]  Sum of 3 internal angles of a triangle (in Euclidean geometry).

[Math.]  Sum of 3 internal angles of a triangle is less than 180o in hyperbolic (Lobachevskian) geometry.

[Math.]  1803 = 63+73+83+…+693 = 5,832,000.

[Measure]  The number of drops in tablespoon.

U.S. customary units for kitchen measurements: ½ pints = 1 cup = 8 fluid ounces = 16 tablespoons = 48 teaspoons = 2880 drops = 236.588 ml.

[Tech.]  Automobile Tire’s Speed Rating

 Tire Rating L M N P Q R S Max. Speed (mph) Max. Speed (kph) 75 120 81 130 87 140 93 150 100 160 106 170 112 180 Tire Rating T U H V W Y Max. Speed (mph) Max. Speed (kph) 118 190 124 200 130 210 149 240 168 270 186 300

[World]  The ISO country code for Congo (was Zaire). (ISO-3166)

180-189

[Library]  Numbers 100-199 are the first 3 digits in Dewey Decimal Classification System call numbers for library books in Philosophy, Psychology and Ethics… Numbers 180-189 are for books in Ancient, Medieval and Oriental Philosophy.