Math
posted by Hannah .
I am looking for help integrating using u substitution over the interval of 0 to pi/2 the function cos(2x/3)

the perimeter of parallelogram is 52cm,and jk is 2cm longer than jm.
find jk
find jm 
Integrate cos (2x/3) dx
u = 2x/3
du = 2/3 dx
3/2 du = dx
I = integrate symbol
I cos (2x/3) dx = I cos u 3/2 du
I cos (2x/3) dx = 3/2 I cos u du
I cos (2x/3) dx = 3/2 sins u
since, u = 2x/3
I cos (2x/3) dx = 3/2 sin (2x/3) 
I cos (2x/3) dx = 3/2 sin (2x/3)
sorry, forgot 0 to pi/2
3/2 sin 2/3 (pi/2)  3/2 sin 0
3/2 sin (2pi/6)  0
3/2 sin (pi/3)
3/2 (sqrt3/2)
3 sqrt3/4