(1)求sin795°的值；(2)已知cosφ=,φ∈(0,),求sin(φ-).

(1)求sin795°的值；

(2)已知cosφ=

,φ∈(0,

),求sin(φ-

答案

解析:(1)原式=sin(720°+75°)=sin75°

=sin(45°+30°)

=sin45°cos30°+cos45°sin30°

(

(2)∵cosφ=

,φ∈(0,

∴sinφ=

∴sin(φ-

)=sinφcos

-cosφsin

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(1)求sin795°的值；(2)已知cosφ=,φ∈(0,),求sin(φ-).

答案

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