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sum of interior angles
(n-2)180
number of diagonals of any polygon is:
n(n-3)/2
pythagorean theorem
a
2
+ b
2
= c
2
special right triangles
3-4-5
6-8-10
12-16-20
5-20-25
5-12-13
10-24-26
8-15-17
7-24-25
the presence of long legs in a right triangle signifies that...
the missing side should be determined by the means of x
2
- y
2
= (x+y)(x-y)
special right triangle 45-45-90
the legs have ratio
x:x:x(sq root)
If the legs of a right triangle are equal
the triangle is necessarily a 45-45-90
30-60-90 triangle has angles
x: x( cubed root): 2x
if the length of the hypotenuse of a right triangle doubles the length of one of its legs...
it is a 30-60-90
how many 30-60-90 triangles are in a hexgon?
twelve
in similar triangles the ratio of the areas of two similar triangles is equal to...
the square of the ratio of the corresponding sides
area of a triangle
1/2 * base * height
area of rectangle and square
length * width
area of parallelogram or rhombus
base times height
area of a rhombus as well is...
diagonal 1 * diagonal 2/ 2
area of a trapezoid
base 1 * base 2 / 2 * height
area of a circle
pie * r
2
circumference of a circle
2pie *r
circumference of a circle
2 * pie * r or pie * d
pie = 22/7
length of an arc
2 * pie * r * x/360
length of a sector of a circle
pie * r
2
* x/ 360
Inscribed angle properties
1. the inscribed angle of an arc is always half the measure of its central angle
2. inscribed angles drawn to the same arc have equal measures.
3. the inscribed angles of equal measure have arcs of equal length and arcs of equal length have inscribed angles of equal measure.
inscribed and circumscribed polygons
1. an inscribed or circumscribed polygon always has the same center as the circle.
2. is a triangle is inscribed in a circle so that one of its sides is the diameter of the circle then that triangle is always a right triangle.
volume of rectangular solid
length * wideth * height
surface area of rectangular solid
2 (lw +wh+ hl) or sum of the area of its faces.
diagonal of rectangular solid...
square root of l
2
+ w
2
+ h
2
volume of a cube
volume of a cube
s
3
surface area of a cube
6s
3
diagonal of a cube
s square root of 3
volume of a cylinder
pie *r
2
* height
surface area of a cylinder
2 * pie * r * h + 2 (pie * r
2
)
Author
kaytea1112
ID
28708
Card Set
geometry
Description
arrrr
Updated
2010-08-02T12:40:09Z
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