求值cos^2α+cos^2(α+120)+cos^2(α+240) 2 ;y=(sinα+1)(cosα+1)求最大最小值2;是第二题的意思

来源：学生作业帮助网编辑：作业帮时间：2024/04/28 12:45:22

x��R�N�0��N�VH��T��R""�d�PD$(/�P�.�h�.|_Q�b��!&X�sϹ��'A��ȫ��d��D P��y��}�b�v�Q��#%j��U.��B��φ��]vѓ�B��q:��$�I��Q\�W��#�B��^�\Ci��A��T=�%ҭ��Nݶ��ݢ �F_#��6�J��|/��9��/��x�*ϛV"+b��K; ��)��}a��|MG�e�*�T�!&')w�<{ũ��Gu�y�$�G6�ˁ��j�HG�~�O5qSL

求值cos^2α+cos^2(α+120)+cos^2(α+240) 2 ;y=(sinα+1)(cosα+1)求最大最小值2;是第二题的意思
求值cos^2α+cos^2(α+120)+cos^2(α+240) 2 ;y=(sinα+1)(cosα+1)求最大最小值
2;是第二题的意思

求值cos^2α+cos^2(α+120)+cos^2(α+240) 2 ;y=(sinα+1)(cosα+1)求最大最小值2;是第二题的意思
1.原式=cos²a+cos²(a+120°)+cos²(a-120°)
=cos²a+1/2[1+cos(2a+240°)]+1/2[1+cos(2a-240°)]
=cos²a+1+1/2[cos(2a+240°)+cos(2a-240°)]
=cos²a+1+cos2acos240°
=3/2+1/2cos2a-1/2cos2a
=3/2.
2.y=sinacosa+sina+cosa+1
令sina+cosa=x,则sinacosa=1/2[(sina+cosa)²-1]=1/2(x²-1).
y=1/2(x²-1)+x+1
=1/2x²+x+1/2
=1/2(x+1)².
当x=-1时取最小值0；当x=根号2时取最大值3/2+根号2.

求值：cos^2α-sin^2α 求值cos^2a+cos^2(a+120°)+cos^2(a+240°) 求值cos^2α+cos^2(α+120)+cos^2(α+240) 2 ;y=(sinα+1)(cosα+1)求最大最小值2;是第二题的意思求值Cos pai/17 *cos 2pai/17*cos 4pai/17*cos 8pai/17 求和：cos(0)+cos(α)+cos(2α)+cos(3α)+……cos(nα) 若tanα=根号下2,求值2×（sinα)^2-sinαcosα+(cosα)^2. 求值【sin(2π-α)sin(π+α)cos(-π-α)】/【sin(3π-α)-cos(π-α)】若tanα=2,化简求值：sinα cosα分之sinα-cosα第一个是+ 求值:sin^2α+sin^2β-sin^2α×sin^2β+cos^2α×cos^2β 求值化简：sinα*cosα tanα=1/2,求(sin^2α+cos^2α)/2cos^2α+2sinαcosαRT...求值已知cosα=√3/3,化简并求值:(1+(tan2α)^2)[cos(2α+π/3)+cos(2α-π/3)] 2cos^2 22.5 - 1求值 cos(3π/2 - π/3),求值求值:cos(arcsin√3/2)= 求值cos(arcsin3/5+2arctan2) 求值∫dx/(cos^2 x) 求值:cos(π/11)cos(2π/11)cos(3π/11)cos(4π/11)cos(5π/11)