sin5xsin7x

毋淑耍2756求∫sin2xcos3xdx的不定积分
傅南海17531458764 ______ 这是基本积分,但是由于现在的高中数学把积化和差公式不做要求.因此学生感觉不熟. 此题用公式sinαcosβ=[sin(α+β)+sin(α-β)]/2,就有

毋淑耍2756...做中间变量,最后化出来是∫2 - 4sin^(x/2) dsin^(x/2),但是结果却不是这样的,但是明明我这样化没错啊,最后也可以得出结果吧?求解2.sin5xsin7x的不定积... -
傅南海17531458764 ______[答案] 我倒着看哈,5,-号带进去因该是ln(1/(-x+√(x^2-a^2)))+c吧

毋淑耍2756解方程 sinxsin7x=sin3xsin5x -
傅南海17531458764 ______ cos(8x)=cos(x+7x)=cosxcos7x-sinxsin7x cos(8x)=cos(3x+5x)=cos3xcos5x-sin3xsin5x sinxsin7x=sin3xsin5x cosxcos7x=cos3xcos5x cosxcos7x+sinxsin7x=cos3xcos5x+sin3xsin5x cos(6x)=cos(x) 根据图像得:(1)6x=x+(k*360) x=72k(k属于自然数) 或 (2)6x+x=2k*180 x=360/7*k(k属于自然数)

毋淑耍2756求∫√(cosx - cos^3 x)dx 有木有高手? -
傅南海17531458764 ______[答案] 里面=cos(1-cos^2)=cos*sin^2 开根号=根号cos *sinxdx=-根号cos dcosx 后面就不用说了吧

毋淑耍2756解方程SinXSin7X=Sin3XSin5X -
傅南海17531458764 ______ 原式可化为如下:sinX(sin3Xcos4X+cos3Xsin4X)=sin3X(sinXcos4X+cosXsin4X) 乘入化简后,得 sinXcos3X=sin3XcosX 即 sin3XcosX-cos3XsinX=0 cos4X=0 所以4X=π/2+kπ/4 X=π/8+kπ/16

毋淑耍2756解方程 sinxsin7x=sin3xsin5x -
傅南海17531458764 ______[答案] cos(8x)=cos(x+7x)=cosxcos7x-sinxsin7x cos(8x)=cos(3x+5x)=cos3xcos5x-sin3xsin5x sinxsin7x=sin3xsin5x cosxcos7x=cos3xcos5x cosxcos7x+sinxsin7x=cos3xcos5x+sin3xsin5x cos(6x)=cos(x) 根据图像得: (1) 6x=x+(k*360) x=72k(k属于自然数) ...

毋淑耍2756求 (1)∫sin2xcos3x dx (2)∫cosx(cosx/2) dx(3)∫sin5xsin7x dx (4)∫cos²(wt+a)dt -
傅南海17531458764 ______ (1):sin2x * cos3x = (1/2) * [sin(2x+3x) + sin(2x-3x)]= (1/2) * [sin5x + sin(-x)]= (1/2) * (sin5x - sinx) ∫ sin2x * cos3x dx= (1/2)∫ (sin5x - sinx) dx= (1/2) * [(-1/5)cos5x - (-cosx)] + c= (1/10) * (5cosx - cos5x) + c(2):cosx * cos(x/2) = (1/2) * [cos(x+x/2) + cos(x-x/...

毋淑耍2756解方程SinXSin7X=Sin3XSin5X如上 -
傅南海17531458764 ______[答案] 原式可化为如下: sinX(sin3Xcos4X+cos3Xsin4X)=sin3X(sinXcos4X+cosXsin4X) 乘入化简后,得 sinXcos3X=sin3XcosX 即 sin3XcosX-cos3XsinX=0 cos4X=0 所以4X=π/2+kπ/4 X=π/8+kπ/16

毋淑耍2756cos3x*tan5x=sin7x 解方程 -
傅南海17531458764 ______[答案] cos3xsin5x=cos5xsin7xsin(5x+3x)-sin(5x-3x)=sin(7x+5x)-sin(7x-5x)sin(8x)=sin(12x)所以可以得到8x+12x=360°n+180°(n属于整数)所以解得x=18°n+9°(n属于整数)或者8x+12x=360°n(n属于整数)解得x=18°n(n...

毋淑耍2756解方程cos3xtan5x=sin7x
傅南海17531458764 ______ 解:cos3xtan5x=sin7x cos3x(sin5x/cos5x)=sin7x cos3xsin5x=sin7xcos5x两边用积化合差公式展开为sin形式,得(sin8x+sin2x)/2=(sin12x+sin2x)/2sin8x=sin12x 8x+2kπ=12x或8x+12x=π+2kπ4x=2kπ或20x=π+2kπx=kπ/2或x=(π+2kπ)/20