tan2a=2tana/(1-tan^2a)=(3/4*2)/(1-9/16)=3/2*16/7=24/7tan(2a-Pai/4)=(tan2a-tanPai/4)/(1+tan2atanPai/4)=(24/7-1)/(1+24/7)=17/31
tan2α=2tanα/(1-tan²α)=24/7原式=(tan2α-tanπ/4((1+tan2αtanπ/4)=17/31
31分17