cos(兀/8)^4-sin(兀/8)^4得于多少

计算sin兀/8cos兀/8 三角化简sin(x-5兀)cos[(-兀/2)-x]cos(8兀-x)/sin[x-(3兀/2)]sin(-x-4兀) sin^2(兀/8)-cos^2(兀/8) 2cos+7tan兀-4sin二分之3兀-8cos二分之兀等于 d/dx sin^8(cos(4x)) cos(兀/8)^4-sin(兀/8)^4得于多少 化简4sin派/8*cos派/8*(cos^2派/8-sin^2派/8) 证明一个sin&cos的等式证明 1+sin^2(x)+sin^4(x)+sin^6(x)=[1-sin^8(x)]/[cos^2(x)] 8sin(45+a)sin(45-a)=1,sin^4a-cos^4a= cosA+cos^2A=1,sin^2A+sin^4A+sin^8A 已知a属于（0,π/2）,且2sin^2 a-sin a cos a-3cos^2 a=0,求SIN(a+兀/4)/SIN 2a+COS 2a+1的值^2表示平方 答案是8分之根号26 化简sin(α-5π)/cos(3π-α)×cos(π/2-α)/sin(α-3π)×cos(8π-α)/sin(-α-4π) cos(-17兀/4)-sin(-17兀/4)= cos^6(π/8)-sin^6(π/8)=求值,[cos^2(π/8)-sin^2(π/8)][cos^4(π/8)+sin^4(π/8)+cos^2(π/8)sin^2(π/8)]=cos(π/4)[1-cos^2(π/8)sin^2(π/8)]=cos(π/4)[1-[sin^2(π/4)]/4]==7√2/16 若x=兀/12 sin^4-cos^4= sin[兀/3 + arc cos(-1/4)] 的值 cos(兀-2a)/sin(a-兀/4）=-跟号2/2求cos(a)+sin(a) sin^4π/8 +cos^4π/8