Three integrals are given that, although they look similar, may require different techniques of integration. fvaluate the integrals. $($Remember the constant of integration.$)$

$($a$){\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}2si{n}^2(x)dx$

$($b$){\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}2si{n}^3(x)dx$

$($c$){\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}2sin(2x)dx$