(Because, remember, a SAS date is simply an integer representing the count of days since Jan 1, 1960.) The SAS date for "30 days ago" is simply today()-30. They answer questions such as, "what happened in the past 30 days?" or "how much activity in the past 6 months?" When I have SAS date values, going back 30 days is simple. Many of my SAS jobs are in support of date-based reports. Looking back at dates in SASīut you know who likes to look at the past? Managers (and probably a few of my colleagues.). I live in the present and I look towards the future - as all citizens of the world should. Weren't my kids so cute back then? It's true, they were - but I don't pine for those days. Sometimes it works and I share them with friends. They think, "We have a collection of photos from this month/day from some previous year - let's collect those together and then prey on Chris' nostalgia instincts." These apps are performing the simplest of date-based math to trick me. Every day, my view of Google Photos or Facebook shows me a collection of photos from exactly some number of years ago to remind me of how good things were back then. "Triangle Properties.Social media has brought anniversary dates to the forefront. Radius of circumscribed circle around triangle, R = (abc) / (4K) References/ Further ReadingĬRC Standard Mathematical Tables and Formulae, 31st Edition New York, NY: CRC Press, p. 512, 2003. Radius of inscribed circle in the triangle, r = √ Triangle semi-perimeter, s = 0.5 * (a + b + c) Solving, for example, for an angle, A = cos -1 If a, b and c are the lengths of the legs of a triangle opposite to the angles A, B and C respectively then the law of cosines states:Ī 2 = c 2 + b 2 - 2bc cos A, solving for cos A, cos A = ( b 2 + c 2 - a 2 ) / 2bcī 2 = a 2 + c 2 - 2ca cos B, solving for cos B, cos B = ( c 2 + a 2 - b 2 ) / 2caĬ 2 = b 2 + a 2 - 2ab cos C, solving for cos C, cos C = ( a 2 + b 2 - c 2 ) / 2ab Solving, for example, for an angle, A = sin -1 Law of Cosines If a, b and c are the lengths of the legs of a triangle opposite to the angles A, B and C respectively then the law of sines states: You could also use the Sum of Angles Rule to find the final angle once you know 2 of them. Use The Law of Cosines to solve for the angles. Given the sizes of the 3 sides you can calculate the sizes of all 3 angles in the triangle. Use the Sum of Angles Rule to find the last angle SSS is Side, Side, Side Use The Law of Cosines to solve for the remaining side, bĭetermine which side, a or c, is smallest and use the Law of Sines to solve for the size of the opposite angle, A or C respectively. Given the size of 2 sides (c and a) and the size of the angle B that is in between those 2 sides you can calculate the sizes of the remaining 1 side and 2 angles. Sin(A) a/c, there are no possible trianglesĮrror Notice: sin(A) > a/c so there are no solutions and no triangle! use The Law of Sines to solve for the last side, bįor A a/c, there are no possible triangles.".use the Sum of Angles Rule to find the other angle, B.
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