23/07/04 06:33:21.76 3g3N8PW6.net
>>205
作図して計算
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> calc(a=5,b=3,c=4)
AEFC AF2
36 65
オマケ
calc=\(a=5,b=3,c=4){
abc2ABC <- function(a,b,c){
A=c*exp(1i*acos((c^2+a^2-b^2)/(2*c*a)))
B=0i
C=a+0i
c(A,B,C)
}
ABC2S <- function(A,B,C) abs(Im((A-C)*Conj(B-C)))/2
angle <- function(B,A,C){
a=c(Re(A),Im(A)); b=c(Re(B),Im(B)); c=c(Re(C),Im(C))
ab=b-a
ac=c-a
dot=sum(ab*ac)
acos(dot/sqrt(sum(ab^2))/sqrt(sum(ac^2)))
}
ABC=abc2ABC(a,b,c)
A=ABC[1]
B=ABC[2]
C=ABC[3]
theta=angle(A,B,C)
E=a*exp(1i*(theta+pi/2))
F=-1i*a
c(AEFC=ABC2S(A,E,F)+ABC2S(A,F,C),AF2=abs(A-F)^2)
}