(tan^2a-cot^2a)/(sin^2a-cod^2a)=sec^2a+csc^2a2是指2次方与a不在一起

(tan^2a-cot^2a)/(sin^2a-cod^2a)=sec^2a+csc^2a2是指2次方与a不在一起
(tan^2a-cot^2a)/(sin^2a-cod^2a)=sec^2a+csc^2a
2是指2次方与a不在一起

(tan^2a-cot^2a)/(sin^2a-cod^2a)=sec^2a+csc^2a2是指2次方与a不在一起
(tan²a-cot²a)/(sin²a-cos²a)
=(sin²a/cos²a-cos²a/sin²a)/(sin²a-cos²a)
=(sin^4 a-cos^4a)/(sin²a*cos²a)(sin²a-cos²a)
=(sin²a-cos²a)(sin²a+cos²a)/(sin²a*cos²a)(sin²a-cos²a)
=(sin²a+cos²a)/(sin²a*cos²a)
=sin²a/(sin²a*cos²a)+cos²a/(sin²a*cos²a)
=1/cos²a+1/sin²a
=sec²a+csc²a