| [ guest ] in KIDS 글 쓴 이(By): guest (픽터) **uge00 Guest Auth Key: a299a2e1c21169668e0cfefef184a458 날 짜 (Date): 2011년 11월 28일 (월) 오전 12시 46분 01초 제 목(Title): Re: [픽터] 초딩 산수 ㅋㅋㅋㅋ 8888888888888888888888888888888888888888888888888888888888888888888 8_[A]___________________88888____8__[E]_________________________[B]_8__ 8__________________8888_________88_________________________________8__ 8______________888_____________8_8_________________________________8__ 8___________8_________________8__8_________________________________8__ 8________8___________________8___8________________________________98__[P] 8______8____________________8____8_______________________[m]___99_8__ 8_____8____________________8_____8___________________________99____8__ 8___8_____________________8______8________________________99_______8__ 8__8_____________________8_______8_____________________99__________8__ 8_8_____________________8________8__________________99_____________8__ 8_8____________________8_________8_______________99________________8__ 88____________________8__________8____________99___________________8__ 8____________________8___________8_________99______________________8__ 8___________________8____________8______99_________________________8__ 8__________________8_____________8___99____________________________8__ 8 _[Q]____________8______________8_[O]_____________________________8__ 8888888888888888888888888888888888888888888888888888888888888888888 8_______________8______________998_________________________________8__ 88_____________8____________99___8_________________________________8__ 88____________8__________99______8_________________________________8__ 88___________8________99_________8_________________________________8__ 8_8_________8_______99___________8_________________________________8__ 8__8_______8_____99______________8_________________________________8__ 8__88_____8____99________________8_________________________________8__ 8____8___8__99___________________8_________________________________8__ 8_____8_8________________________8_________________________________8__ 8____998__[M]____________________8_________________________________8__________ 8_99__8__8_______________________8_________________________________8___ 99___8_____888___________________8_________________________________8___ 8___8__________888_______________8_________________________________8___ 8__8______________888888_________8_____________________________________ 8_8_____________________88888____8_D___________________________________ 8888888888888888888888888888888888888888888888888888888888888888888888 C 99직선이 원과 만나는 점을 M, m이라고 할때, [M]의 좌표는 (1/5, 2/5) [m]의 좌표는 (1 + 4/5, 1 + 3/5)이다. pi /4 = 원의 1/4의 넓이 = 부채꼴(QOD) = 부채꼴(QOM) + 부채꼴(MOD) 인데 부채꼴(MOE)가 atan(2)였듯이, 부채꼴(MOD)는 atan(1/2) 이다. 부채꼴(QOM) = atan(tan(각(PQO))) = atan(tan(각(mQO))) = atan([3/5]/[1+4/5]) = atan((3/5)/(9/5)) = atan(1/3) 그래서 pi/4 = atan(1/2) + atan(1/3) 이다. 물론 이것은 당연한건데 tan(a+b) = [tan(a) + tan(b)]/[1-tan(a)tan(b)] 이기 때문. 야튼간에, pi/4 = atan(1/2) + atan(b); 이라면, b = tan(atan(b)) = tan(pi/4 - atan(1/2)) = [1-1/2]/[1+1/2] = 1/3 인데, 그냥 기하학적으로 저게 무슨 관련이 있나 싶어서. |