zmkmkkk
幼苗
共回答了19个问题采纳率:89.5% 举报
亲爱的楼主:
cos2α/sin(α-π/4)=-√2/2(cos^2α-sin^2α)/(sinαcosπ/4-cosαsinπ/4) = -√2/2[(cosα+sinα)(cosα-sinα)] / [√2/2(sinα-cosα)] = -√2/2-√2(cosα+sinα)(cosα-sinα) / (cosα-sinα) = -√2/2-√2(cosα+sinα) = -√2/2cosα+sinα = 1/2
祝您步步高升
1年前
9