若cos(π/4+x)=3/5,7/12π

三角函数解方程 (cos 3x)^3+ (cos 5x)^3 = 8 (cos 4x)^3 (cos x)^3 若cos(π/4+x)=3/5,7/12π 化简sin(x)(cos(x)+cos(3x)+cos(5x)+cos(7x)) 已知cos（x+45º)=3／5且17π/12＜x＜7π/4,求(sin2x+2cos²x)／1-tanx的值注意!括号里加的是cos^2x cos(π/4+x)=3/5,17π/12 cos(π/4+X)=3/5,17π/12 cos(π/4+x)=3/5,17π/12 cos(π/4+x)=3/5,17π/12 cos(π/4+x)=3/5,17/12π cos(π/4+x)=3/5,17π/12 cos(π/4+x)=3/5,17π/12 cos(π/4+x)=3/5,-17π/12 若cos(x+y)=4/5,cos(x-y)=-4/5,且3π/2 若cosx=2/3,x是第四象限角,求sin(x-2π)+sin(-x-3π)cos(x-3π)/cos(π-x)-cos(-π-x)cos(x-4π)的值 若函数f(x)=[2cos^3 x-sin^2 (x+π)-2cos (-x-π)+1]/[2+2cos^2(7π+x)+cos(-x)],（1）求证f(x)是偶函数若函数f(x)=[2cos^3 x-sin^2 (x+π)-2cos (-x-π)+1]/[2+2cos^2(7π+x)+cos(-x)],（1）求证f(x)是偶函数 （2）求f(π/3)的值 已知cos[x+(π/4)]=3/5,7π/12 若cos(π/4+x)=3/5 17π/12 若cos（π/4+x）=3/5,17/12π