tanα=3/5,α为锐角,求 (4cosα-5sinα)/(2cosα+3sinα)

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tanα=3/5,α为锐角,求(4cosα-5sinα)/(2cosα+3sinα)tanα=3/5,α为锐角,求(4cosα-5sinα)/(2cosα+3sinα)tanα=3/5,α为锐角,求(

tanα=3/5,α为锐角,求 (4cosα-5sinα)/(2cosα+3sinα)
tanα=3/5,α为锐角,求 (4cosα-5sinα)/(2cosα+3sinα)

tanα=3/5,α为锐角,求 (4cosα-5sinα)/(2cosα+3sinα)
sinα/cosα=tanα=3/5
sinα=(3/5)cosα
原式=(4cosα-3cosα)/[2cosα+(9/5)cosα]=5/19

(4cosα-5sinα)/(2cosα+3sinα)=(4-5tanα)/(2+3tanα)=1/(19/5)=5/19