ACT Math Formulas Flashcards
What is Pi(r^2)
The area of a circle
What is the area of a circle
A=Pi(r^2)
What is 2Pir=Pid
Circumference
(When d=diameter)
What is the circumference equation
C=2Pir=Pid
Area of a triangle
A=1/2bh
What does A=1/2bh solve
Area of a triangle
Pythagorean theorem
a^2+b^2=c^2
What does a^2+b^2=c^2 solve
The hypotenuse of a triangle
A of n= A of 1(r)^n-1
Geometric sequence (nth term)
Geometric sequence (nth term)
A of n= A of 1(r)^n-1
Arithmetic sequence (nth term)
a of n= a of n-1 + d
Or: a of n = a+ (n-1)d
a of n= a of n-1 + d
Or: a of n = a+ (n-1)d
Arithmetic sequence (nth term)
Common difference
D= a of 2 — a of 1
Sum of Geo Sequence terms
s of n= (A of 1(r)^n-1))/ r-1
Sum of infinite geo sequence
s of infinity = a/1-r
Sum of n terms of arithmetic sequence
S of n = (n/2)[ a of 1 + a of n]
Or: S of n = (N/2)[ 2a+(n-1)d]
