Mensuration/ Geometry Flashcards
Area of a rectangle
length * base
Area of a trapezium
1/2(a+b)h
Area of a triangle
1/2 (base * height)
Area of a parallelogram
A = base * height
Circumference of a circle
π * diameter
Area of a circle
π * r²
Diameter of a circle
2 * radius
Area of a sector (of a circle (like a slice))
a/360 * πr²
Lenght of an arc
a/360 * πD
Cylinder, Surface Area
Curved Surface Area
π * 2r * h
Total Surface Area
(π * 2r * h) + (2 * π * r²)
Sector
Area in a circle enclosed by two radii
eg. a pie slice.
Segment
An area of a circle enclosed by a chord and an arc.
(As if someones sliced off the edge of a pie)
(work out area by working out the triangle of the sector and minusing)
Arc
Segment of the circumference of a circle
Two angles opposite each other in an ‘x’
Vertically opposite
Two angles on same side of line intersecting a parallel pair of lines. (forms an ‘F’ shape)
Corresponding angles
‘Z’ shaped angles, Opposite angles formed by an intersecting line of two parallel lines.
Alternate angles
Exterior angle formula
360/ number of sides of the polygon
eg. 360/3 = 180
Interior angle formula
(n - 2) * 180 = Sum of the interior angles
n = number of sides
((n-2)*180) / n = 1 interior angle
Congruent
Identical
Similar
The shapes have the same ‘shape’ + interior angles. (Probably just enlarged or diminished)
Scale factor
Number by which a line gets multiplied to enlarge/ diminish.
New line/ Original line
Linear vs Area vs Volume scale factor
Linear = linear sf.
Area = [linear sf]²
Volume = [linear sf]³
Pythagoras
a² + b² = c²
