Root system inner product is the Killing form. The cosine of the angle between two roots is constrained to be a half-integral multiple of a square root of an integer. This is because formula_32 and formula_33 are both integers, by assumption, and formula_34 Since formula_35, the only possible values for formula_36 are formula_37 and formula_38, corresponding to angles of 90°, 60° or 120°, 45° or 135°, 30° or 150°, and 0° or 180°. Condition 2 says that no scalar multiples of "α" other than 1 and -1 can be roots, so 0 or 180°, which would correspond to 2"α" or −2"α", are
Olympic triangle to re-align the course to the new wind direction. With a 60, 60, 60 triangle, if the wind shifts 15 degrees either way, one of the reaching legs will be a 45-degree broad reach, while the other will be at 75 degrees to the wind and will be a close reach. Many dinghy classes have a target length for a race for the first boat. This time might take into consideration the age of competitors, how physically demanding the class is and how physically demanding the conditions are. 100 minutes is often used by Herons in Australia as an informal