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求值[tan(-330)cos(-570)cos150sin(-420)]/[cos(-420)sin(-690)]

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求值[tan(-330)cos(-570)cos150sin(-420)]/[cos(-420)sin(-690)]
求值[tan(-330)cos(-570)cos150sin(-420)]/[cos(-420)sin(-690)]
[tan(-330)cos(-570)cos150sin(-420)]/[cos(-420)sin(-690)]
=[tan(-360+30)cos(-720+150)cos150sin)]/[cos(-360-60)sin(-720+30)](360度整倍数直接拿出)
=[tan(30)cos(150)cos150sin(-60)]/[cos(-60)sin(30)]
= -[tan(30)cos(30)cos30sin(60)]/[cos(60)sin(30)](sin(-60)为-,cos(-60)为正cos150=-
cos30 ,cos30sin(60)=cos30,cos(60)=sin(30))
=-cos(30)cos30/sin(30)
=(-3/4)/(1/2)
=-3/2