化简:sin方(a-30°)+sin方(a+30°)—sin方a

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化简:sin方(a-30°)+sin方(a+30°)—sin方a化简:sin方(a-30°)+sin方(a+30°)—sin方a化简:sin方(a-30°)+sin方(a+30°)—sin方asin^

化简:sin方(a-30°)+sin方(a+30°)—sin方a
化简:sin方(a-30°)+sin方(a+30°)—sin方a

化简:sin方(a-30°)+sin方(a+30°)—sin方a
sin^2(a-30°)+sin^2(a+30°)-sin^2a
=(sinacos30°-cosasin30°)^2+(sinacos30°+cosasin30°)^2-sin^2a
=(√3/2*sina-1/2*cosa)^2+(√3/2*sina+1/2*cosa)^2-sin^2a
=3/2*sin^2a+1/2*cos^2-sin^2a
=1/2*sin^2a+1/2*cos^2a
=1/2(sin^2a+cos^2a)
=1/2.