Math Flashcards
(16 cards)
Total degrees of a polygon where n = # of sides
180(n-2)
Average degrees per side or degree measure of congruent polygon
180* ( (n-2)/n )
Area of triangle
1/2 * b * h
An isosceles right triangle (45-45-90) has sides in a ratio of
x * x * x sqrt(2)
A 30-60-90 triangle has sides in a ratio of
x * x sqrt(3) * 2x
Sets of numbers for each side of certain right triangles:
3-4-5
5-12-13
8-15-17
7-24-25
Basic triangle side rule
兩邊之和大於第三邊
Arc length
x/360 * 2πr
Area of sector
x/360 * πr^2
Formula of a line
y=mx+b
Formula of slope
m=(y1-y2)/(x1-x2)
The slope of two lines which are perpendicular to each other, if one slope is x, what is the slope of the other line?
-1/x
The distance formula
Sqrt( (x2-x1)^2 + (y2-y1)^2 )
Formula of sequence: 1+2+3+…+n is
n(n+1)/2
If 27/4 has reminder 3 and 6/4 has reminder 2 what’s the reminder of (27+6)/4?
R1+R2 = 3+2 -4 =1
Because 3+2 is 5 which is larger than the divisor 4, hence we subtract the sum by divisor!
What is the reminder of 2/11
2
Every fraction that the numerator is greater than the denominator, the reminder is the numerator