Question

1 已知cosa=-3/5 且a是第二象限角,则tana的值

Answer 1

1.tana=sina/cosa=4/5/(-3/5)=-4/3

2.a∈(0,π/2)

3.1/sina×cosa=1/tana=1/2

4.tana=1或1/2；sina-3cosa/sina+cosa=-1或-5/3

5.1/tana=(k²-1)/(k²-2k-3)

6.cos1200°=cos(1080+120)°=cos(3*360+120)°=-1/2

7.cos（-11π/3）=cosπ/3=1/2

很高兴为你解答,希望对你有所帮助,