若sinacosa=1/3,0

问题描述:

若sinacosa=1/3,0

数学人气:616 ℃时间:2020-10-01 07:40:54
优质解答
sin^2a+cos^2a=1
(Sina+cosa)^2-2 Sina cosa= Sin^2a+ cos^2a
(Sina+cosa)^2=1+2/3=5/3
(Sina-cosa)^2+2 Sina cosa= Sin^2a+ cos^2a
(Sina-cosa)^2=1-2/3=1/3
因为0
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sin^2a+cos^2a=1
(Sina+cosa)^2-2 Sina cosa= Sin^2a+ cos^2a
(Sina+cosa)^2=1+2/3=5/3
(Sina-cosa)^2+2 Sina cosa= Sin^2a+ cos^2a
(Sina-cosa)^2=1-2/3=1/3
因为0