Question

当∠B=∠C时,化简tan【（A+B）/2】+tanC/2...算出角度...

Answer 1

a=180-b-c

(a+b)/2=(180-c)/2=90-c/2

所以原式=tan(90-c/2)+tanc/2

=sin(90-c/2)/cos(90-c/2)+sin(c/2)/cos(c/2)

=cos(c/2)/sin(c/2)+sin(c/2)/cos(c/2)

=[cos²(c/2)+sin²(c/2)]/sin(c/2)/cos(c/2)

=1/(1/2*sinc)

=2/sinc