Formulas Flashcards
Sphere volume
4/3 pi R^3
Sphere surface area
4 pi R^2
Parallelogram
a*b
Rhombus
ab/2
Trapezoid
1/2(ab)*h
Sum of interior angles
180*(n-2)
Cone volume
1/3 * (Pi * r^2 * h)
Diagonal of rectangle
SqRt (a^2 * b^2 * c^2)
Diagonal of square
SqRt(3)*a
45-45-90 triangle
1 : 1 : SqRt(2)
30-60-90 triangle
1 : SqRt(3) : 2
y = mx+b
y - y1 = (y2-y1)/(x2-x1) * (x-x1)
Thale’s theorem
For a triangle inscribed in a circle with all 3 vertices on the circle’s circumference:
If one side is the diameter,
Then angle opposite diameter is 90 degrees
Investment value with simple interest
V = P*(1 + rt)
Investment value with compound interest
V = P*(1+r/n)^(nt)
Combination formula
N choose k
n! / ( k! * (n-k)! )
Essence of combinations
Creating two groups, just determining what’s “in” and what’s “out”.
So an equal number of combinations results from choosing K as from choosing N-K. Choosing K is choosing ways K can be in, while choosing N-K is choosing ways K can be out.