Area and Perimeter Flashcards
Area of a triangle
Half times by base x height
A = 0.5 x base x height
Area of a parallelogram
Area = base x height
Area of trapezium
On the formula sheet
Area = 0.5(a + b)h
Area = half x sum of parallel sides x distance between them
How do you find the perimeter of a shape?
Add up all the lengths
The distance around a shape
Circumference of a circle
Circumference = πd
Circumference = pi times by diameter
when I need a circumference I’ll just use pi d
Area of a circle
Area = πr²
Area = pi times by radius squared
pi r squared sounds like area to me
How do you find the radius if you know the diameter?
Half it!
Radius = diameter ➗ 2
How do you find the diameter if you know the radius?
Double it!
Diameter = radius x 2
Area of a semicircle
Half the area of a full circle
Aiming high?
Length of arc
Arc length = fraction x circumference
Arc length = degrees/360 x πd
= degrees/360 x 2πr
Aiming high?
Area of a sector (pizza slice)
Sector area = fraction times by area of circle
Sector area = degrees/360 x πr²
Area of a rectangle
Length x width
