Trig on DAT?

[sweetdaises2000]

Hey guys, I was wondering what specific trig identities or formulas are needed to not miss any trig questions?? Anyone who has taken the exam, pleaseee comment. I know the basics-sohcahtoa and things like csc=1/sin. But do we need to know double angle formulas, like sin(2x)=2sinxcosx ? Just how much is needed to do well. If I need to memorize anything I'd like to do it now, not the day before lol

Thanks guys!

---

Members don't see this ad.

 

[slm266]

Hey guys, I was wondering what specific trig identities or formulas are needed to not miss any trig questions?? Anyone who has taken the exam, pleaseee comment. I know the basics-sohcahtoa and things like csc=1/sin. But do we need to know double angle formulas, like sin(2x)=2sinxcosx ? Just how much is needed to do well. If I need to memorize anything I'd like to do it now, not the day before lol

Thanks guys!

I think one of those appeared on a topscore QR, but I don't remember about the actual DAT. You can't get any SDNers to guarantee you that you won't have to know them, so you might as well play it safe and know them.

 

[mprs]

you may or may not need to know the double angle formula! (PS: you do )

Umm you obviously need to know sin^2x + cos^2x = 1. You also need to know the different derivations of it (i.e dividing the equation by sin^2x or cos^2x)

 

[sweetdaises2000]

Hey mpr, thanks for your input.
Please take a look at this site: http://www.sosmath.com/trig/Trig5/trig5/trig5.html
I know the formulas up until the quotient formulas, I also know one of the double angle formulas:sin(2x)=2.sinx.cosx. Which derivations are u referring to? Do I have to memorize the derivations on that site? Please be specific...

 

[mprs]

I was talking about the pythagorean identities. Notice how if you divide the first one by cos^2 you get the 2nd one, and if you divide the first by sin^2 you get the 3rd one.

From my experience:

You need to know:

Reciprocal Identities: Pretty standard
Pythagorean Identities: If you know the first one, you know them all
Quotient Identities: Pretty standard
Co-function Identities: You need to understand this. I don't think its necessary to memorize every single one, but draw a unit circle and put a few examples and see how it works. Once you see how it works, you won't need the formulas and you can just do the questions as they come.
Even-Odd Identities: See above. No real need for memorization, just understand the concept so you can replicate it.
Double Angle Formulas: TBH I had a sin one, and most tests I've done only had the sin one. However, I don't see why they couldn't ask cos or tan. I'd memorize these to be safe.

Everything else memorize only if you have the time. There will never ever ever be more than 1 question on any of the other stuff, if that. I have never seen them in all my practice tests or the real thing.