Formulas

Question 1

Sphere volume

Answer 1

4/3 pi R^3

Question 2

Sphere surface area

Answer 2

4 pi R^2

Question 3

Parallelogram

Answer 3

a*b

Question 4

Rhombus

Answer 4

ab/2

Question 5

Trapezoid

Answer 5

1/2(ab)*h

Question 6

Sum of interior angles

Answer 6

180*(n-2)

Question 7

Cone volume

Answer 7

1/3 * (Pi * r^2 * h)

Question 8

Diagonal of rectangle

Answer 8

SqRt (a^2 * b^2 * c^2)

Question 9

Diagonal of square

Answer 9

SqRt(3)*a

Question 10

45-45-90 triangle

Answer 10

1 : 1 : SqRt(2)

Question 11

30-60-90 triangle

Answer 11

1 : SqRt(3) : 2

Question 12

y = mx+b

Answer 12

y - y1 = (y2-y1)/(x2-x1) * (x-x1)

Question 13

Thale’s theorem

Answer 13

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

Question 14

Investment value with simple interest

Answer 14

V = P*(1 + rt)

Question 15

Investment value with compound interest

Answer 15

V = P*(1+r/n)^(nt)

Question 16

Combination formula

N choose k

Answer 16

n! / ( k! * (n-k)! )

Question 17

Essence of combinations

Answer 17

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.