Q.2 If A = cos20 + sin40, then for ...
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Q.2 If A = cos20 + sin40, then for all value of [AIEEE-2011] (A) 1 SAS 2 (B) Asi Q.8 If cosec (C) Asi (D) None of these 0.3 In a APQR if 3 sin P + 4 cos 0 = 6 and

JEE/Engineering Exams
Maths
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[ begin{aligned} A &=cos ^{2} theta+sin ^{4} theta Rightarrow A=& sin ^{4} theta+1-sin ^{2} theta &=sin ^{4} theta-sin ^{2} theta+1 end{aligned} ] ( Rightarrow A=left(sin ^{2} theta-frac{1}{2}right)^{2}+frac{operatorname{sen} 3}{4} ) - A man when, ( sin ^{2} theta frac{1}{2}=0 ) [ Rightarrow A_{min }=frac{3}{4} ] Amax, when ( sin ^{2} theta-frac{1}{2} ) is max, [ begin{aligned} & 0 leq sin ^{2} theta leq 1 Rightarrow quad-frac{1}{2} & leq sin ^{2} 0-frac{1}{2} leq 1 / 2 therefore quad A max &=left(frac{1}{2}right)^{2}+frac{3}{4}=7 end{aligned} ] [ therefore quad frac{3}{4} leq A leq 1 ] (B) Ans
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