sinb等于什么公式,secx等于什么

解决数学问题啦,要具体步骤
两角和差公式推导:sina sinb=sin(a b/2(a-b/2 sin(a b/2(a
lecture 43 prove(sina sinb(cosa cosb=tan(a b/2]
两角和公式:sin(ab=sinacosb cosasinbsin(a-b=sinacosb-cosa
问答列表 需要4个公式(1 sina=cos(90度-a(2 cosb=sin(90度