YR 8 - Formulas Flashcards
What is the equation for the area of a rectangle?
length x width
What is the equation for the area of a triangle?
1/2 base x width
What is the equation for the area of a parallelogram?
base x height
What is the equation for the area of a trapezium?
1/2 (a+b) x height
[a+b are parallel lines]
What is the equation for percentage change?
actual change - original ÷ original x 100
What is the equation for simple interest?
amount (£) + (years x interest (%) of amount (£))
What is the equation for the volume of a 3D shape?
area of cross section x its length (unit³)
What is the equation for the area of a circle?
πr²
What is the equation for the circumference of a circle?
πd
What is the equation for the gradient?
change in y ÷ change in x
What is the equation for the equation of a line?
y = ⅿₓ + ⅽ (m = gradient, c = y-intercept)
What is the equation for the sum of interior angles of a polygon?
(n-2) x 180 (n is the number of sides on the polygon)
What is the equation for Pythagoras Theorem?
a² + b² = c² (a is the shortest side, b is the middle-length size)
What do you do if you have to find a and b instead of c?
Substitution
What is the equation for standard form?
a x 10ⁿ (a is between 1 and 10)
