Okay, so after what felt like the longest week ever, it's now time to do the blog. This week in Calculus BC I was kinda discouraged by trig sub because its something i really don't understand. I only do the problems right when i have the formulas in front of me...and after studying them for a week straight, and still getting mixed up on them, i'm finding it almost hopeless.
Hopefully someone can show me their study techniques?
But lets go over a few things...
For trig sub, something i always get wrong is WHEN to actually do the method..so, i believe it is when you can't basically bi-part something? correct?
Also, you should never bi-part or trig sub things when you only have the trig function and its derivative/ integral..just saying. I do it all the time and it is definately the hard way.
I really wish there is something i can explain that i know how to do, but there really isn't..
I guess i'll explain Wallis Formula.
So, you do this when you have sin or cos and the degree is EVEN:
1. Start with 1/2 and multiply the chronological numbers until you get to the exponent.
2. Then multiply by pi/two
3. Add +c
4. Box or circle your answer
When the degree is ODD:
1. Start with 1/2 and multiply the chronological numbers unitl you get to the exponent.
2. Put a + c
3. Box or circle your answer
So, i really feel like a baby and hopefully someone can help me..
i really just need all the helpful hints and basic problems explained to me.
i'm not quite sure why my brain hasn't kicked into school mode yet..
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Tips for trig integration:
ReplyDelete1. If you see a sin or cos or tan to an ODD power, take out a couple of squares. those squared ones, you're then going to convert using your trig identities. (i.e. sin^2+cos^2=1 etc...)
2. If sec is even, you want everything to eventually be in terms of tangent with a sec^2 left over (i.e. your du).
3. If sec is ODD, BY PARTS
4. If all else fails, try converting everything to sin and cos.
hope it helps you out!