已知tana=2（1）sina+3cosa/sin - 知识问答

已知tana=2（1）sina+3cosa/sina-cosa（2）sin²a+sinacosa+3cos

2个回答

（1）sina+3cosa/sina-cosa
=(tana+3)/(tana-1)
=(2+3)/(2-1)
=5
（2）sin²a+sinacosa+3cos²a
=(sin²a+sinacosa+3cos²a)/(sin²a+cos²a)
=(tan²a+tana+3)/(tan²a+1)
=(4+2+3)/(4+1)
=9/5

相关问题