cos(5*3.1415926..)/8 * cos (3.1415926../8)=多少3.1415926＝派

cos(5*3.1415926..)/8 * cos (3.1415926../8)=多少3.1415926＝派 cos（5π/8）*cosπ/8 cos(5π/8)*cos（π/8)= 化简cos^8(π/8)+cos^8(3π/8)+cos^8(5π/8)+cos^8(7π/8) cos^2 π/8+cos ^2 3π/8+ cos^2 5π/8+cos^2 7π/8=? 三角函数解方程 (cos 3x)^3+ (cos 5x)^3 = 8 (cos 4x)^3 (cos x)^3 函数 (4 20:28:50)cos^4 (π /8)+cos^4(3π/8)+cos^4(5π/8)+cos^4(7π/8) = 不用计算器,求(cos(π/8))^4+(cos(3π/8))^4+(cos(5π/8))^4+(cos(7π/8))^4的值 不用计算器求值 cos^派/8加cos^4 3派/8加cos^4 5派/8加cos^4 7派/8 已知8cos(2α+β)+5cosβ=0,cos(α+β)×cosα≠0,求tan(α+β)×tanα=? cos(π/32)*cos(π/16)*cos(π/8)= cos 5π/8 cos π/8 + sin 5π/8 sin π/8= cos (180/5)* cos(360/5)=? 计算：cos（π/5)+cos（2π/5)+cos(3π/5)+cos(4π/5) cos=-3/5, 求值Cos pai/17 *cos 2pai/17*cos 4pai/17*cos 8pai/17 求SINπ/64 COSπ/64 COSπ/32 COSπ/16 COSπ/8 cos(π/17)*cos(2π/17)*cos(4π/17)*cos(8π/17)