QR Trig

[dentalwhiz]

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My DAT is in 2 days. I didn't go over the trig identities, like negative identities and double angle identities because I've read threads that they are not adding it to the test anymore. It is making me weary because I haven't been scoring to well particularly on Math Destroyer as a result (I am pretty well off otherwise). I also don't know the ellipses formulae. Are these things I should have down before my test?

 

[DallasCowboys]

I wouldn't try and spend your final two days cramming trig formulas into your brain, from what I have seen there is less trig showing up on recent DATs but as far as I know it is still a possibility to show up on your test. So do your best to know some of the more common trig identities and that should be fine. You should know the ellipse and circle formulas (it's not too bad) as well as the area and volume formulas for cylinders, spheres, etc. since those are common questions. If you have DAT Bootcamp, there are some new "quantitative comparison" questions that bootcamp does a great job covering, and it is important to go over those.

 

[Faefly]

Sin(2x)=2sin(x)cos(x)

Cos(2x)=cos^2(x)-sin^2(x)

Sin^2(x)+cos^2(x)=1

sin(-x)=-sin(x) because it's an odd function

cos(-x)=cos(x) because it's an even function

sin x= cos (90-x)
cos x= sin(90-x)

cos=1/sec

sin=1/csc

so yeah s&c to remember not c&c
S&C

tan=1/cot

Let's practice.

Simplify the following

sin(4x)/(2cos(2x)*csc(2x))

ok let's do this

sin(4x)=2sin(2x)*cos(2x)
csc(2x)=1/sin(2x)

cool let's get back to the equation at hand
2sin(2x)*cos(2x)/(2*cos(2x) *(1/sin(2x))
Get rid of cos(2x) they are the same
and flip 1/sin(2x) when it goes up it becomes sin(2x)

you get:

2 sin(2x) * sin (2x)/2

get rid of the 2

final result= sin^2(2x)

volia!

See it's not that hard, and this question is similar to a question on the destroyer, I changed some stuff in it.

If you are worried, just do some questions in ( qr destroyer )not math destroyer about them, because they are easier there, so you get familiar with them, don't worry about something and then you don't do anything about it!

If you worry do something to get rid of the fear.

 

[artist2022]

I would say no, because the test doesn't have straight-up trig problems, they just have problems that require some knowledge of trig, like 30-60-90 triangles, 45-45-90 triangles (their relative sides), and SohCahToa. You do need to know the Volume and Surface Area formulas for: cylinders, spheres, cubes
Hope this helps 🙂

 

[dentalwhiz]

Thanks for the replies. I know all the V/SA formulas, QC problems, SOHCAHTOA, special triangles etc. but not the actual trig identities. I'll get the ellipses equation figured out then as well.

 

[dentalwhiz]

Sin(2x)=2sin(x)cos(x)

Cos(2x)=cos^2(x)-sin^2(x)

Sin^2(x)+cos^2(x)=1

sin(-x)=-sin(x) because it's an odd function

cos(-x)=cos(x) because it's an even function

sin x= cos (90-x)
cos x= sin(90-x)

cos=1/sec

sin=1/csc

so yeah s&c to remember not c&c
S&C

tan=1/cot

Let's practice.

Simplify the following

sin(4x)/(2cos(2x)*csc(2x))

ok let's do this

sin(4x)=2sin(2x)*cos(2x)
csc(2x)=1/sin(2x)

cool let's get back to the equation at hand
2sin(2x)*cos(2x)/(2*cos(2x) *(1/sin(2x))
Get rid of cos(2x) they are the same
and flip 1/sin(2x) when it goes up it becomes sin(2x)

you get:

2 sin(2x) * sin (2x)/2

get rid of the 2

final result= sin^2(2x)

volia!

See it's not that hard, and this question is similar to a question on the destroyer, I changed some stuff in it.

If you are worried, just do some questions in ( qr destroyer )not math destroyer about them, because they are easier there, so you get familiar with them, don't worry about something and then you don't do anything about it!

If you worry do something to get rid of the fear.

That doesn't seem to bad, I was just wondering if it was even necessary to attempt to remember these with the sparing amount of time I have left. I definitely agree that if worried about something to learn it anyways, but my time could be better spent on other things at this point with the scarce amount I have left. I'll try and fit some time to learn the basics of these problems.

 

[Faefly]

That doesn't seem to bad, I was just wondering if it was even necessary to attempt to remember these with the sparing amount of time I have left. I definitely agree that if worried about something to learn it anyways, but my time could be better spent on other things at this point with the scarce amount I have left. I'll try and fit some time to learn the basics of these problems.

Yeah, I think if you know the simple identities and stuff, that more than enough considering in their guide, they don't mention trig anymore, but people said they got 2-3 questions on the simple side!
So, yeah I would not worry too much, anyway.
Remember to relax on the day before the test and sleep early.
Best of luck on your test!