慜>>148
>>157 BC=併[4r^2-{(2r-3)^2/(2r+3)^2}]
>>161 sin兤=t/r
cos兤=併{1-(t/r)^2}
=(3^2+4^2-4t^2)/2񑧈
=(25-4t^2)/24
(25-4t^2)^2/24^2=1-t^2/r^2
(25-4t^2)^2^2=24^2(1-t^2)
r^2=24^2(1-t^2)/(25-4t^2)^2
sin兤=t/併{24^2(1-t^2)/(25-4t^2)^2}
=t(25-4t^2)/24併(1-t^2)
僺僞僑儔僗偺掕棟傛傝丄
(3sin兤)^2+(4-3cos兤)^2=4t^2
9sin^2兤+16-24cos兤+9cos^2兤=4t^2
9(1-cos^2兤)+16-24cos兤+9cos^2兤=4t^2
25-24cos兤=4t^2
t^2=25/4-6cos兤
sin兤=t(25-4t^2)/24併(1-t^2)
=cos兤併(25/4-6cos兤)/併(1-25/4+6cos兤)
=cos兤併(25-24cos兤)/併(24cos兤-19)
sin^2兤=cos^2兤(25-24cos兤)/(24cos兤-19)
2sin兤cos兤=(cos^2兤-sin^2兤)(25-24cos兤)/(24cos兤-19)
2sin兤cos兤(24cos兤-19)=(1-2sin^2兤)(25-24cos兤)
48sin兤(1-sin^2兤)-38sin兤cos兤=25-50sin^2兤-24cos兤+48sin^2兤cos兤
48sin兤-48sin^3兤-38sin兤cos兤=25-50sin^2兤-24cos兤+48sin^2兤cos兤
拞抐