1.2cot^2x+cotx-3
ãåæ两个æ¬å·ç¸ä¹çæ ¼å¼ï¼æ¯å¦(tanx-2)(tanx+4)ã
=(2cotx+3)(cotx-1)
2.cos^2xtanx-2cosxtanx-3tanx
æççæ¡æ¯tanx(cosx+1)(cosx-3),è§å¾ä¸å¤ªå¯¹ã
=tanx(cos^2x-2cosx-3)
=tanx(cosx+1)(cosx-3),对
3.ï¼cscx+1ï¼/(cscx-1) = (1+sinx)/(1-sinx)
ãè¯æçå·ä¸¤è¾¹ç¸çã
左边=ï¼cscx+1ï¼/(cscx-1)
åååæ¯åä¹ä»¥sinxï¼
=ï¼cscxsinx+sinxï¼/(cscxsinx-sinx)
= (1+sinx)/(1-sinx) = å³è¾¹ï¼å¾è¯
4.ï¼1-2cos^2xï¼/(1-2cosxsinx) = (sinx+cosx)/(sinx-cosx)
左边=ï¼1-2cos^2xï¼/(1-2cosxsinx)
å°1=sin^2x+cos^2x代å
¥ï¼
=(sin^2x+cos^2x-2cos^2xï¼/(sin^2x+cos^2x-2cosxsinx)
=(sin^2x-cos^2xï¼/(sinx-cosx) ^2
=(sinx+cosx)(sinx-cosxï¼/(sinx-cosx) ^2
=(sinx+cosx)/(sinx-cosx)=å³è¾¹ï¼å¾è¯
温馨提示:答案为网友推荐,仅供参考