(sin²a-sin²b)/(sina·cosa-sinb·cosb) 如何化简,

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(sin²a-sin²b)/(sina·cosa-sinb·cosb)如何化简,(sin²a-sin²b)/(sina·cosa-sinb·cosb)如何化简,

(sin²a-sin²b)/(sina·cosa-sinb·cosb) 如何化简,
(sin²a-sin²b)/(sina·cosa-sinb·cosb) 如何化简,

(sin²a-sin²b)/(sina·cosa-sinb·cosb) 如何化简,
(sin²a-sin²b)/(sina·cosa-sinb·cosb) = (sin a-sin b)(sin a+sin b)/(sin(a-b)) = 2*(cos (a+b)/2)*(sin (a-b)/2)*2*(sin (a+b)/2)*(cos (a-b)/2)/(2*sin((a-b)/2)*cos((a-b)/2))=2*(cos(a+b)/2)*(sin(a+b)/2) = sin(a+b)
用到了和差化积