化简根号下(1)1-cos^2 240 (2)tana分之根号下1-cos^2 a(a为第二象限角)
问题描述:
化简根号下(1)1-cos^2 240 (2)tana分之根号下1-cos^2 a(a为第二象限角)
答
1-cos^2 240
=1- cos^2 60
=1- 1/2
=1/2
(1-cos^2 a)/ tana
=sin^2 a / tana
=sina cosa