已知tana=1/2tan(a-p)=-2/5则tan(2a-p)的值
问题描述：
已知tana=1/2tan(a-p)=-2/5则tan(2a-p)的值
答
tana=1/2,tan(a-p)=-2/5
tan(2a-p)
=tan[a+(a-p)]
=[tana+tan(a-p)]/[1-tanatan(a-p)]
=(1/2-2/5)/(1+1/2*2/5)
=(5-4)/(10+2)
=1/12