Let ∣M∣ denote the determinant of a square matrix M.
Let g:[0,2π]→R be the function defined by
where g(θ)=f(θ)−1+f(2π−θ)−1f(θ)=211−sinθ−1sinθ1−sinθ1sinθ1+sinπsin(θ−4π)cot(θ+4π)cos(θ+4π)−cos2πloge(4π)tan(θ−4π)loge(π4)tanπ
Let p(x) be a quadratic polynomial whose roots are the maximum and minimum values of the function g(θ), and p(2)=2−2.
Then, which of the following is/are TRUE ?
g(θ)=f(θ)−1+f(2π−θ)−1f(θ)=21det(A)+det(B),θ∈[0,2π]p(x):roots =maxg(θ),ming(θ);p(2)=2−2Which of (1)–(4) are TRUE?Plan: 1.detA,2.detB,3.f=1+sin2θ4.g=sinθ+cosθ,5.p from its rootsA=1−sinθ−1sinθ1−sinθ1sinθ1detA=(1+sin2θ)−sinθ(0)+(1+sin2θ)=2(1+sin2θ)sin(θ−4π)=−cos(θ+4π)tan(θ−4π)=−cot(θ+4π),ln4π=−lnπ4B=0−cdc0−L−dL0,BT=−Bodd-order skew-symmetric⇒detB=0f(θ)=21detA+detB=1+sin2θg(θ)=sin2θ+sin2(2π−θ)=∣sinθ∣+∣cosθ∣θ∈[0,2π]⇒g(θ)=sinθ+cosθg(θ)=2sin(θ+4π)maxg=2,ming=1p(x)=k(x−1)(x−2)p(2)=k(1)(2−2)=2−2⇒k=1p(x)=(x−1)(x−2)=x2−(1+2)x+2p(x)<0⟺1<x<2(1)x=43+2∈(1,2)⇒p<0TRUE(2)x=41+32∈(1,2)⇒p<0FALSE(3)x=452−1>2⇒p>0TRUE(4)x=45−2<1⇒p>0FALSETRUE statements: (1)and(3)