如下
如图
x= atantx^2 =a^2.(tant)^2x^2+a^2 =a^2.(tant)^2+a^2x^2+a^2 =a^2.(sect)^2sect =√(x^2+a^2 )/a
sect=1/sint,tant=sint/cost,sint2+cost2=1,自己连列计算就出来了
tant=x/a (a≠0)1+tan²t=1+sin²t/cos²t=1/cos²tsect=1/cost=根号下1+tan²t=根号下1+x²/a²=根号下x²+a²/a