Secx. Cos5x+1=0 solve this question
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SecXcos5X+1=0 or, secXcos5X=-1 or, cos5X=-1/secX or, cos5X=-cosX or, cos5X+cosX=0 or, 2cos(5X+X)/2cos(5X-X)/2=0 or, cos3Xcos2X=0 or, (4cos³X-3cosX)(2cos²X-1)=0. Either, 4cos³X-3cosX=0 or, 4cos³X=3cosX or, cos²X=3/4 or, cosX=√3/2 (neglecting the negative sign) ∴, cosX=cos30°
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