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Question Number 115348 by bemath last updated on 25/Sep/20

If x ∈ (0,(π/2)) and 2cos x(sin x+cos x)+tan^2 x < sec^2 x   has solution set is a<x<b. find the  value of a+b

Ifx(0,π2)and2cosx(sinx+cosx)+tan2x<sec2x hassolutionsetisa<x<b.findthe valueofa+b

Answered by bobhans last updated on 25/Sep/20

⇒sin 2x+2cos^2 x+tan^2 x < 1+tan^2 x  ⇒sin 2x+2((1/2)+(1/2)cos 2x) < 1  ⇒sin 2x+cos 2x < 0  we get ((3π)/8) < x < ((4π)/8) →then a+b = ((7π)/8)

sin2x+2cos2x+tan2x<1+tan2x sin2x+2(12+12cos2x)<1 sin2x+cos2x<0 weget3π8<x<4π8thena+b=7π8

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