Respostas

2013-09-20T16:27:24-03:00
Sen(mx)cos(nx) = 1/2[sen(m+n)x+sen(m-n)x]
S sen(2x)cos(5x)dx = S 1/2 [sen(7x) - sen(3x)]dx = - (1/14)cos(7x) +(1/6)cos(3x) + constante

A melhor resposta!
2013-09-21T09:41:37-03:00
A=5x  b=2x
cos(a+b)=cos(a).cos(b)-sen(a).sen(b)
cos(a-b)=cos(a).(cos(b)+sen(a).sen(b)
cos(a+b)+cos(a-b)=2cos(a).cos(b)
cos(a).cos(b)=1/2[cos(a+b)+cos(a-b)]
integral1/2[cos(5x+2x)+cos(5x-2x)]dx
1/2integralcos(7x)dx + 1/2integralcos(3x)dx
1/2.1/7integral7cos(7x)dx + 1/2.1/3integral3cos(3x)dx
1/14sen(7x)+1/6sen(3x)+ C
1 5 1