Posted by **Hannah** on Monday, January 17, 2011 at 7:20pm.

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

- Math -
**jennifer**, Monday, January 17, 2011 at 7:22pm
the perimeter of parallelogram is 52cm,and jk is 2cm longer than jm.

find jk

find jm

- Math -
**helper**, Monday, January 17, 2011 at 7:37pm
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)

- Math -
**helper**, Monday, January 17, 2011 at 7:46pm
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

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