Equations :) Flashcards
What is the formula for finding the midpoint?
(x1 + x2) divided by 2 , (y1 + y2) divided by 2
For example,
(-1 + 3) divided by 2 , (5 + -9) divided by two would mean you would end up with a midpoint of (1,-2)
You can also do the same but with Z to work out the 3D midpoint :)
What is the formula for gradient of a line?
X2 - X1
What is the formula for percentage change?
percentage change = difference in amounts
——————————— x 100
original price
What is the formula for percentage increase?
New amount = original amount x multiplier^period of time
What is the formula for compound growth and compound decay?
Compound Growth:
Pn = initial amount x ( 1 + rate % of growth ) ^ period of time
———————
100
Compound Decay:
Pn = initial amount x ( 1 - rate % of growth ) ^ period of time
———————
100
What is the formula for estimating population sizes?
Total marked Total recaptured
————————- = ————————-
Total population
What is the formula for interpretting data from a pie chart?
Frequency = angle size
————— x Total frequency
360
What is the formula for area of a rectangle?
Area = Base x Height
What is the formula for area of a triangle?
Area = Base x Height
———————
2
What is the formula for area of a parallelogram?
Area = Base x Height
What is the formula for area of a trapezium?
Area = (a + b) x height
———————-
2
a is the length of the top bit and b is the length of the bottom bit. Height is the height at the largest point in the trapezium.
What is the formula for perimeter of a circle?
C =Pi x diameter
What is the formula for area of a circle?
A = Pi x r^2
What is the formula for arc length of a sector of a circle?
arc length = theta x Pi x d
———
360
What is the formula for sector area?
sector area = theta x Pi x r^2
———
360
