cos(45-a)•cos(45+a)=1/3,sin^4 a+cos^4 a=____
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cos(45-a)•cos(45+a)=1/3,sin^4a+cos^4a=____cos(45-a)•cos(45+a)=1/3,sin^4a+cos^4a=____cos(
cos(45-a)•cos(45+a)=1/3,sin^4 a+cos^4 a=____
cos(45-a)•cos(45+a)=1/3,sin^4 a+cos^4 a=____
cos(45-a)•cos(45+a)=1/3,sin^4 a+cos^4 a=____