tan(a-π/4)=1/2 (1)求tana的直 (2)求sin2a-cosa的平方的直
问题描述:
tan(a-π/4)=1/2 (1)求tana的直 (2)求sin2a-cosa的平方的直
答
(1)tan(a-π/4)=1/2(tana-tanπ/4)/(1+tanatanπ/4)=1/2(tana-1)/(1+tana)=1/22tana-2=1+tanatana=3(2)sin2a-cos²a=(2sinacosa-cos²a)/(sin²a+cos²a)=(2tana-1)/(tan²a+1)=(2×3-1...