化简 [ sin(270°+B) × sin(90°-B) × cot(B-270°) ] / [ sin(-B) ×
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化简 [ sin(270°+B) × sin(90°-B) × cot(B-270°) ] / [ sin(-B) × cos(270°-B) × cot(180°-B) ]
要完整,
要完整,
[sin(270°+B) × sin(90°-B) × cot(B-270°) ] / [ sin(-B) × cos(270°-B) × cot(180°-B)]
=[-cosBcosB(-tanB)]/[(-sinB)(-sinB)(-cotB)]
=-[cosBcosBtanB]/[sinBsinBcotB]
=-cotBcotBtanB/cotB
=-1
=[-cosBcosB(-tanB)]/[(-sinB)(-sinB)(-cotB)]
=-[cosBcosBtanB]/[sinBsinBcotB]
=-cotBcotBtanB/cotB
=-1
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