Average value problem

[Atmosphere]

Hi, new here. Anyway, my problem is at the very end of an average value problem. Basically I've done 90% of the problem, I just can't figure out how to manipulate my answer to look like one of the multiple-choice.





Hopefully you can see and read that. I crossed out B,C,and D simply because I'm almost positive the denominator has to be 8. Basically it's the sin of -3 that's giving me a problem...I don't really know how to alter it. I'm probably making an obvious mistake, but any help would be much appreciated, thank you!

 

[Deleted member 4993]

Hi, new here. Anyway, my problem is at the very end of an average value problem. Basically I've done 90% of the problem, I just can't figure out how to manipulate my answer to look like one of the multiple-choice.


View attachment 2624


Hopefully you can see and read that. I crossed out B,C,and D simply because I'm almost positive the denominator has to be 8. Basically it's the sin of -3 that's giving me a problem...I don't really know how to alter it. I'm probably making an obvious mistake, but any help would be much appreciated, thank you!

Use the well-known identity:

sin(- Θ) = - sin(Θ)

 

[Atmosphere]

Knew it was something simple. Anyway, thank you.