Question

sina+cosa=1/2,tana+cota=

rt

Answer 1

sina+cosa=1/2
两边平方
(sina)^2+(cosa)^2+2sinacosa=1/4
1+2sinacosa=1/4
sinacosa=-3/8

tana+cota=sina/cosa+cosa/sina=[(sina)^2+(cosa)^2]/(sinacosa)
=1/(sinacosa)
=-8/3

Answer 2

sina+cosa=1/2
(sina＋cosa)^2=1/4
1+2sina*cosa=1/4
sina*cosa=-3/8
tana+cota
＝sina/cosa+cosa/sina
=1/cosa*sina
=-8/3

Answer 3

因为sina+cosa=1/2
所以（sina+cosa)的平方=1/4
sinacosa= -3/8
tana+cota=1/sinacosa=-8/3