Liệu cos^3x có thể được sử dụng để mô tả các hiện tượng trong vũ trụ không? cos^3x

Let x = cos 200. Then we get, from the formula for cos 3x,. 4x3-3x=4 cos3 20?-3 cos 200 =cos 3(200)= . .. 8x3=6x+1. We now have cos 200 cos 400 cos 800. =x(2x2 ... Yc = C₁+ C₂. e* sin(*) + (₂ ex cos(x). Ус. C3. ® Particular solution: look for solution in the form. Ур. As in (3x) + B cos (3x). Yp = 3 A cos (3x) - 3B Sin ... (cos(x) + isin(x)). 3. = cos(3x) + isin(3x). By comparing coefficients, we have cos(3x) = cos. 3. (x) − 3 sin. 2. (x) cos(x) and sin(3x) = 3 sin(x) cos. 2. 4. Trial and error. Ex 1. = tan 3x. S dx cos 3x. =S. ← trigonometric substition sin 3x | cos 3x cos 3x. 5213x. Cosx dx u = Ja dx. (1-cos²x) sanx dx. 1053X. 1-42. (d) cos(3x)sin(3x)dx. ∫ . 5. Evaluate the integral. 0 exp(2sin )cos x x dx π. ∫ . 6. Evaluate cos(2 ) x x dx π π-. ∫. Oct 27, 2015 ... Prove the trig identity: cos 3a = 4cos^3 x - 3cos x Apply the trig identity: cos (a + b) = cos a.cos b - sin.a.sin b. cos 3x = cos (2x + x) ... = !e2X sin 3x + ~e2X cos 3x - if e2x cos 3x dx. 3. 9. 9. => (1 + ~) f e2x cos 3x dx = ~e2X sin 3x + ~e2X cos 3x f e2x. => e2x cos 3x dx = 13(3 sin 3x + 2 cos 3x) ... Nov 2, 2014 ... [tex]cos \alpha +cos \beta =2\cdot cos \frac{ \alpha + \beta }{2} \cdot cos \frac{ \alpha - \beta }{2}\\-----------------\\\\ \alpha =3x\ ... Yp = -9 A Cos 3x-9B Sin 3x. Plug into ODE: (-9A (os 3x-98 Sin 3x)+4(-3A Sin 3x + 3B Cos3x). + 4 CA Cos 3x + B Sin 3x). = [-5A ]. T-5. +12B Cos 3x + -12A-5B ... Differentiate wrt x \sin(x)\left(121\left(\sin(x)\right)^{2}\left(\cos(x)\right)^{4}-75\left(\cos(x)\right)^{2}\left(\sin(x)\right)^{