tan(π/4+a)=2,求1/(2sinacosa+cosa^2)值我做出tana=1/3,tan2a=3/4,原式=1/(sin2a+cos2a+sina^2)接下来就不会了...

tan(π/4+a)=2,求1/(2sinacosa+cosa^2)值我做出tana=1/3,tan2a=3/4,原式=1/(sin2a+cos2a+sina^2)接下来就不会了...
tan(π/4+a)=2,求1/(2sinacosa+cosa^2)值
我做出tana=1/3,tan2a=3/4,原式=1/(sin2a+cos2a+sina^2)
接下来就不会了...

tan(π/4+a)=2,求1/(2sinacosa+cosa^2)值我做出tana=1/3,tan2a=3/4,原式=1/(sin2a+cos2a+sina^2)接下来就不会了...
1/(2sin（a）cos（a）+cos（a）^2)
=(sin（a)^2+cos（a）^2)/(2sin(a)cos(a)+cos(a)^2),
分子分母同除以cos（a）^2得
(tan(a)^2+1)/(2tan(a)+1)
=(1/9+1)/(2/3+1)
=2/3