是求tan(阿尔法+派/4)的值吧
tan(阿尔法+派/4)=tan[(阿尔法+贝塔) -(贝塔-派/4)]
=[ tan(阿尔法+贝塔)- tan(贝塔-派/4)]/[1+ tan(阿尔法+贝塔)•tan(贝塔-派/4)]
=(2/5-1/4)/(1+2/5•1/4)
=3/22.