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Question Number 211732 by BaliramKumar last updated on 19/Sep/24

Answered by TonyCWX08 last updated on 19/Sep/24

Using quadratic formula  x=((sin^2 θ±(√(sin^4 θ + 4cos^2 θ)))/2)    p=((sin^2 θ+(√(sin^4 θ + 4cos^2 θ)))/2)  p^2 =(((sin^2 θ+(√(sin^4 θ + 4cos^2 θ)))/2))^2   p^2 = (((sin^2 θ+(√(sin^4 θ + 4cos^2 θ)))^2 )/4)    q=((sin^2 θ−(√(sin^4 θ + 4cos^2 θ)))/2)  q^2 =(((sin^2 θ−(√(sin^4 θ + 4cos^2 θ)))^2 )/4)    p^2 +q^2 =((sin^4 θ + 2sin^2 θ(√(sin^4 θ+4cos^2 θ ))+ sin^4 θ + 4cos^2 θ +sin^4 θ −2sin^2 θ(√(sin^4 θ+4cos^2 θ))+sin^4 θ+4cos^2 θ)/4)  p^2 +q^2 =((4sin^4 θ + 8cos^2 θ )/4)  p^2 +q^2 =sin^4 θ+2cos^2 θ  Minimum value = 1

Usingquadraticformulax=sin2θ±sin4θ+4cos2θ2p=sin2θ+sin4θ+4cos2θ2p2=(sin2θ+sin4θ+4cos2θ2)2p2=(sin2θ+sin4θ+4cos2θ)24q=sin2θsin4θ+4cos2θ2q2=(sin2θsin4θ+4cos2θ)24p2+q2=sin4θ+2sin2θsin4θ+4cos2θ+sin4θ+4cos2θ+sin4θ2sin2θsin4θ+4cos2θ+sin4θ+4cos2θ4p2+q2=4sin4θ+8cos2θ4p2+q2=sin4θ+2cos2θMinimumvalue=1

Commented by BaliramKumar last updated on 19/Sep/24

first step 4cos^2 θ

firststep4cos2θ

Commented by TonyCWX08 last updated on 19/Sep/24

Edited

Edited

Answered by BHOOPENDRA last updated on 19/Sep/24

p+q=((−b)/a)  p.q=c/a  (p+q)^2 =p^2 +q^2 +2pq  p^2 +q^2 =(p+q)^2 −2pq  p^2 +q^2 = sin^4 θ +2cos^2 θ               =(1−cos^2 θ)^2 +2cos^2 θ   p^2 +q^2  =(1+cos^4 θ)                 =    0≤cos^4 θ≤1                 =     0+1≤cos^4 θ +1≤1+1                  = 1≤cos^4 θ +1≤2  p^2 +q^2 =1 (minimum value)

p+q=bap.q=c/a(p+q)2=p2+q2+2pqp2+q2=(p+q)22pqp2+q2=sin4θ+2cos2θ=(1cos2θ)2+2cos2θp2+q2=(1+cos4θ)=0cos4θ1=0+1cos4θ+11+1=1cos4θ+12p2+q2=1(minimumvalue)

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