tan(a+β)= 2 tan(a-β)= -3/5 则tan2β=?(请给出解析)

问题描述:

tan(a+β)= 2 tan(a-β)= -3/5 则tan2β=?(请给出解析)

tan2β
=tan[(a+β-(a-β)]
=[tan(a+β)- tan(a-β)]/[1+tan(a+β)*tan(a-β)]
=(2+3/5)/(1-6/5)
=-13