函数f(x)等于1 2x-sinx-π 2的零点个数

f(x)=sin²x=(-1/2)(1-2sin²x)+1/2=-(1/2)cos2x+1/2所以f(x)周期是：π

函数f(x)=sin(2x+φ)+根号三cos(2x+θ)=2sin（2x+θ+π/3）的定义域为：R则f(0)=0所以：0=sin（θ+π/3）,=>θ+π/3=2kπ,k∈Z即θ=2kπ-π/3所

f(x)=2cosxsinx-(2cos^2x-1)=sin2x-cos2x=根号2[sin(2x-pi/4)],所以最小正周期为pi,最大值为根号2,最小值为负根号2,

令x=π/3代入f（（π/3）+x)=f（（π/3）-x)f(0)=sinA+1=f(2π/3)=sin((4π/3)-A）+1sinA=sin((4π/3)-A）=sin(4π/3)cosA-cos

∵f(x)＝2sin2x−23sinxsin(x−π2)=2sin2x+23sinxcosx=1−cos2x+3sin2x=1+2sin(2x−π6)∵0＜x＜2π3∴−π6＜2x−π6＜7π6∴−1

/>|x|小于等于派/4,∴sinx∈[0,√2/2]f(x)=-sin^2(x)+sinx+1=-(sinx-1/2)²+5/4∴当sinx=1/2时,f(x)有最大值5/4sinx=0时

π/3+θ=kπ,θ=kπ-π/3,k是整数

0≤sin²x≤0.25所以-0.5≤sinx≤0.5利用三角函数的图像kπ-π/6≤x≤kπ+π/6,k∈Z再问：为何尔来-0.5≤sinx？谢谢！再答：sin²x≤0.25|s

因为f(x)=根号3sin(2x-π/6)+2sin的平方（x-π/12)=根号3sin(2x-π/6)-（1-2sin的平方（x-π/12)）+1=根号3sin(2x-π/6)-cos(2x-π/6

∵f(cosx)=sin3x∴f(sinx)=f[cos(π/2-x)]=sin[3(π/2-x)]=sin(3π/2-3x)=-cos3x选D再问：呃，不太明白怎么变的。。。。。。再答：f()括号内

选Cf(x)=log3(2-4sin²x)f(x)=log3[2(1-2sin²x)]f(x)=log3(2cos2x)f(π/12)=log3{2cos[2*(π/12)]}=l

f(x)=2sinxcosxcosΦ+(12sin^2x)sinΦ=sin2xcosΦ+(6-6cos2x)sinΦ=sin2xcosΦ-6cos2xsinΦ+6sinΦ=根号37*sin(2x+a)

f(x)=sin²(x+π/12)+cos²(x-π/12)=1-cos²(x+π/12)+cos²(x-π/12)=1+[cos(x-π/12)+cos(x+

如果我知识点还没忘记的话,应该是（n+1/12）π,其中n=0,1,2,3,4,.因为sinx根据（2nπ+π/2）对称,列出等式2x+π/3=2nπ+π/2即可

答案：9再问：图中不是只有4个零点？再答：还有两个端点！~再问：看懂了！两个图像有两个零点很接进！再答：祝你开心~

f(x)=√3sin(2x-π／6)+2sin^2(x-π／12)=√3sin(2x-π／6)+1-cos(2x-π／6)=2(√3/2sin(2x-π／6)-1/2cos(2x-π／6))+1=2(

f(x)=[cos(x)+sin(x)]sin(x)=cos(x)sin(x)+sin^2(x)=1/2sin2x+1/2(1-cos2x)=√2/2[cos(p/4)sin2x-sin(p/4)co

f(x)=(sinx)^2+cosx=1-(cosx)^2+cosx=-(cosx)^2+cosx+1设t=cosx|x|≤π/4√2/2≤t≤1y=-t^2+t+1=-(t-1/2)^2+5/4在[

向量b＝（2cos,sinx)f(x)＝2cos^2x＋sinxcosx+1=1/2sin2x+cos2x+2=√5/2sin（2x+Φ）＋2这个函数的周期是π