有题意可知
84 = (1/2)*15*14*sin∠B
即 sin∠B = 4/5
所以 cos∠B = 3/5
所以 AC ^2 = AB^2 + BC^2 - 2AB*BC*cos∠B
= 225 + 196 - 2*15*14*(3/5)
= 169
所以 AC = 13
所以 AC/sin∠B = BC/sin∠A = AB/sin∠C
得到 sin∠A = 56/65
sin∠C = 12/13
所以 tan∠A = 56/33
tan∠C = 12/5
有题意可知
84 = (1/2)*15*14*sin∠B
即 sin∠B = 4/5
所以 cos∠B = 3/5
所以 AC ^2 = AB^2 + BC^2 - 2AB*BC*cos∠B
= 225 + 196 - 2*15*14*(3/5)
= 169
所以 AC = 13
所以 AC/sin∠B = BC/sin∠A = AB/sin∠C
得到 sin∠A = 56/65
sin∠C = 12/13
所以 tan∠A = 56/33
tan∠C = 12/5