Getting to Grips with Intergrating Trig Functions 2

G

Guest

Guest
Please would you be kind enough to look at this for me? Thank You.

\(\displaystyle \L
\int_0^\pi {2\cos (3x + \frac{\pi }{2}} )dx\)

\(\displaystyle \L\
= {\textstyle{2 \over 3}}\left[ {\sin (3x + \frac{\pi }{2})} \right]_0^\pi = {\textstyle{2 \over 3}}\left[ {\sin (3(\pi ) + \frac{\pi }{2}) - \sin (3(0) + \frac{\pi }{2})} \right]\)

\(\displaystyle \L\
= {\textstyle{2 \over 3}}\left[ {\sin \frac{{7\pi }}{2} - \sin \frac{\pi }{2}} \right] = {\textstyle{2 \over 3}}\sin 3\pi\)

:?:
Thank You.
 
everything o.k. except your final evaluation ...

sin(7pi/2) - sin(pi/2) does not equal sin(3pi)

sin(7pi/2) = -1

sin(pi/2) = 1
 
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