<p>OK, I took a practice math section ACT and got a 31.
I know I can improve since I got a 760 on the SAT. I just need to know formulas that are on the test. However, the red book doesn't have anything like that, just tests. Can someone give me a list of formulas that are on the test? (I would say omit simple ones like A=pi(r^2) but there could be a simple formula that I forgot, so don't do that please.)</p>
<p>midpoint: (x+x)/2 , (y+y)/2
slope: (y-y)/(x-x)
distance: (x-x)^2+(y-y)^2 <----------whole thing square rooted
pythagorean triples: 3 4 5, 8 15 17, 7 24 25, 9 40 41
30 60 90 triangles: x xroot3 2x
45 45 90 triangles: x x xroot2
sin cos tan: S(Opposite/Hypotenuse) C(Adjacent/Hyoptenuse) T(Opposite/Adjacent) <—SOHCAHTOA</p>
<p>area of a trapezoid: A = (1/2)(base 1 + base 2)(height)</p>
<p>Thank you!
I did know most of these, but not that 8 15 17, 7 24 25, and 9 40 41 were triples. I only knew 3 4 5 and 5 12 13.
I guess that would explain one of the wrong answers that I got (IIRC) - it means that I should always check if it’s a triple before I do anything else.</p>
<p>Most right triangles on the test are. If not, it is probably either 45/45/90 or 30/60/90</p>
<p>nth term of a geometric series: nth term = ar^(n – 1) <===== a is first term. r is common ratio</p>
<p>nth term of arithmetic series: nth term = a + (n-1)d <======== d is common difference</p>
<p>sum of arithmetic series: sum = n(a1 + an)/2 <========= a1 = first term. an = nth term</p>
<p>sum of FINITE geometric series:
sum = a1(1- r^n)/(1-r)</p>
<p>sum of INFINITE geometric series:
sum = a1 / (1-r)</p>
<p>Mikeypz are those actually on the test? I’ve taken it twice and don’t recall seeing those, also I’ve never learned them so I’m hesitant as to whether I should memorize them for tomorrow’s test.</p>
<p>Well, I don’t think you need to know the finite geom series sum.</p>
<p>And I don’t think the ACT expects you to memorize them, I just thought studying them will be helpful.
For example, I’m pretty sure on one of the ACTs I’ve taken, the math section had a problem in which you could use one of those formulas to get the answer. You didn’t HAVE to, because it was an easy sum/nth-term to find, but knowing the formula definitely sped things up. </p>
<p>But I forget. Maybe that formula would be given at the beginning of the problem or something.</p>
<p>You don’t need to memorize arithmetic/geometric sequence formulas, but they may be handy. In some tests, there is often 1 problem involving a sequence of some sort, but it is solvable without that formula. The formula only expedites solving it.</p>