cos八分之派的平方等于多少COS八分之派的平方减SIN八分之派的平方等于多少
问题描述：
cos八分之派的平方等于多少
COS八分之派的平方减SIN八分之派的平方等于多少
答
cos²π/8=(1+cos2×π/8)/2=(1+cosπ/4)/2=(1+√2/2)/2=(2+√2)/4
cos²π/8-sin²π/8
=cos2×π/8
=cosπ/4
=√2/2
答
COS八分之派的平方减SIN八分之派的平方 = cos( π / 4 ) = √ 2 / 2
答
cos^2(π/8)=±√{[1+cos2(π/8)]/2}.
=±√{[1+cos(π/4)]/2}.
=±√[(1+√2/2)/2].
=±(1/2)√(2+√2).
cos^2(π/8)-sin^2(π/8)=cos2(π/8).
=cos(π/4)
=√2/2.
答
答：
(cosπ/8)^2-(sinπ/8)^2
=cosπ/4
=√2/2
答
cos²(π/8)
=1/2*[2cos²(π/8)-1]+1/2
=1/2*cos(π/4)+1/2
=√2/4+1/2
cos²(π/8)-sin²(π/8)
=cos(π/4)
=√2/2