已知3sina=-cosa,求值 (1)sina-3cosa/sina+3cosa (2)1+sinacosa

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已知3sina=-cosa,求值(1)sina-3cosa/sina+3cosa(2)1+sinacosa已知3sina=-cosa,求值(1)sina-3cosa/sina+3cosa(2)1+si

已知3sina=-cosa,求值 (1)sina-3cosa/sina+3cosa (2)1+sinacosa
已知3sina=-cosa,求值 (1)sina-3cosa/sina+3cosa (2)1+sinacosa

已知3sina=-cosa,求值 (1)sina-3cosa/sina+3cosa (2)1+sinacosa
3sina=-cosa
sina/cosa=-1/3
∴tana=-1/3

(1)sina-3cosa/sina+3cosa
=(tana-3)/(tana+3)
=(-1/3-3)/(-1/3+3)
=-5/4

(2)1+sinacosa
=(sin²a+cos²a+sinacosa)/(sin²a+cos²a)
=(tan²a+1+tana)/(tan²a+1)
=(1/9-1/3+1)/(1/9+1)
=7/10

3sina=-cosa,
(sina)^2+(cosa)^2=1
10(sina)^2=1
(sina)^2=1/10
求值 (1)sina-3cosa/sina+3cosa=(sina-3*(-3sina))/(sina-3*3sina)=10sina/(-8sina)=-5/4
(2)1+sinacosa=1+sina*(-3sina)=1-3*1/10=7/10

由3sina=-cosa,
∴9sina=-3cosa,
(1)(sina+9sina)/(sina-9sina)
=(1+9)/(1-9)
=-5/4.
(2)由3sina=-cosa
∴3sinacosa=-cos²a
-9sin²a+cos²a=0
-10sin²a+sin²a+...

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由3sina=-cosa,
∴9sina=-3cosa,
(1)(sina+9sina)/(sina-9sina)
=(1+9)/(1-9)
=-5/4.
(2)由3sina=-cosa
∴3sinacosa=-cos²a
-9sin²a+cos²a=0
-10sin²a+sin²a+cos²a=0
sin²a=1/10
1+sina(cosa)
=1+sina(-3sina)
=1-3sin²a
=7/10.

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