证明:(1 + tan x) / (sin x + cos x) = 1 / cos x

问题描述:

证明:(1 + tan x) / (sin x + cos x) = 1 / cos x

左*cosx=(cosx+tanx*cosx)/(sin x + cos x)
=(cosx+sinx)/(sin x + cos x)
=1
左=1 / cos x=右

(1+tanx)/(sinx+cosx) = (1+sinx/cosx)/(sinx+cosx) = (sinx+cosx)/cosx/(sinx+cosx) = 1/cosx