Difference between revisions of "User:Saul/algebra"

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== Trigonometry ==
 
== Trigonometry ==
 +
'''Sin(30) = (&radic;1) / 2 = Cos(60)'''<br>
 +
'''Sin(45) = (&radic;2) / 2 = Cos(45)'''<br>
 +
'''Sin(60) = (&radic;3) / 2 = Cos(30)'''<br>
 
=== Various Formulae ===
 
=== Various Formulae ===
'''sin<sup>2</sup>(x) = sin(x) * sin(x)'''<br>
+
'''Sin<sup>2</sup>(x) = Sin(x) * sin(x)'''<br>
'''sin(x<sup>2</sup>) = sin(x * x)'''<br>
+
'''Sin(x<sup>2</sup>) = Sin(x * x)'''<br>
'''tan(x) = sin(x) / cos(x)'''<br>
+
'''Tan(x) = Sin(x) / Cos(x)'''<br>
'''sin<sup>2</sup>(x) + cos<sup>2</sup>(x) = 1'''<br>
+
'''Sin<sup>2</sup>(x) + Cos<sup>2</sup>(x) = 1'''<br>
'''sin(x) = cos(90 - x)'''<br>
+
'''Sin(x) = Cos(90 - x)'''<br>
 +
'''Cos(x) = Sin(90 - x)'''<br>
 
<br>
 
<br>
'''A / sin(a) = C / sin(c) = C / sin(c)'''<br>
+
'''A / Sin(a) = C / Sin(c) = C / Sin(c)'''<br>
'''a<sup>2</sup> = b<sup>2</sup> + c<sup>2</sup> - 2bc * cos (A)'''<br>
+
'''a<sup>2</sup> = b<sup>2</sup> + c<sup>2</sup> - 2bc * Cos (A)'''<br>
 
<br>
 
<br>
 
Note:<br>
 
Note:<br>
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'''&plusmn; = &#8723;; &#8594; + = - &#8594; - = +'''<br>
 
'''&plusmn; = &#8723;; &#8594; + = - &#8594; - = +'''<br>
 
<br>
 
<br>
'''sin(a &plusmn; b) = sin(a) * cos(b) &plusmn; cos(a) * sin(b)'''<br>
+
'''Sin(a &plusmn; b) = Sin(a) * Cos(b) &plusmn; Cos(a) * Sin(b)'''<br>
'''sin(a &plusmn; b) = cos(a) * cos(b) &#8723; sin(a) * sin(b)'''<br>
+
'''Sin(a &plusmn; b) = Cos(a) * Cos(b) &#8723; Sin(a) * Sin(b)'''<br>
 
<br>
 
<br>
'''sin(2a) = 2sin(a) * cos(a)'''<br>
+
'''Sin(2a) = 2Sin(a) * Cos(a)'''<br>
'''cos(2a) = cos<sup>2</sup>(a) - sin<sup>2</sup>(a)'''<br>
+
'''Cos(2a) = Cos<sup>2</sup>(a) - Sin<sup>2</sup>(a)'''<br>
 
<br>
 
<br>
'''sin<sup>2</sup>(a) = ( 1 - cos(2a) ) / 2'''<br>
+
'''Sin<sup>2</sup>(a) = ( 1 - Cos(2a) ) / 2'''<br>
'''cos<sup>2</sup>(a) = ( 1 + cos(2a) ) / 2'''<br>
+
'''Cos<sup>2</sup>(a) = ( 1 + Cos(2a) ) / 2'''<br>
 +
<br>
 +
'''Csc(x) = 1 / Sin(x)'''<br>
 +
'''Cot(x) = 1 / Tan(x) = Cos(x) / Sin(x)'''<br>
 +
'''Sec(x) = 1 / Cos(x)'''<br>
 +
'''Sec<sup>2</sup>(x) = 1 / Cos<sup>2</sup>(x)'''<br>
 +
 
 +
== Quadratics ==
 +
 
 +
=== Turning Point ===
 +
The equation dor the turning point '''x''' value is: '''-b / 2a''', after that y can be derived.
 +
 
 +
=== Complete the Square ===
 +
The completed square looks like this:<br>
 +
'''y = a(x + dx)<sup>2</sup> + dy'''<br>
 +
'''a''' is the shape, a negative value indicates a '''n''' like shape where a positive value indicates a '''u''' like shape and if a is 0 the shape is a flat line.<br>
 +
'''dx''' is the '''negative''' displacement of '''x'''.<br>
 +
'''dy''' is the displacement of '''y'''.
 +
 
 +
==== Formulae ====
 +
To convert a general quadratic to the completed square, use the following formulae:<br>
 +
'''y = ax<sup>2</sup> + bx + c &#8594; a(x + b / 2a)<sup>2</sup> - b<sup>2</sup> / 4a + c'''

Latest revision as of 01:32, 17 March 2020

Combinations and Permutations

Permutations/Pick

A permutation is a sequence where the order does matter.
This is often notated by n pick r where n is the data set - say 40 lotto balls and r is the selection count - say 8 balls.
The general formulae for permutations is:
P = n! / (n-k)!

Combinations/Choose

A combination is a sequence where the order does NOT matter.
This is often notated by n choose r - n and r mean the same thing as in pick.
The general formulae for combinations is:
C = n! / ((n-k)!k!)
Also note that:
n choose k is the same as n choose (n - k)

Binomial Theorem

(a + b)n = k=0Σn ( ( n choose k ) ak bn-k )

Approximation Using Binomial

Calculating a number to the power of another can be approximated by the following formulae:

(1 + x)n = 1 + nx + (n(n-1)x2)/2! + (n(n-1)(n-2)x3)/3! + (n(n-1)(n-2)(n-3)x4)/4! ...

Note: This is unending so the more steps you take the more accurate the number will be, however usually 3-4 steps is enough.

Trigonometry

Sin(30) = (√1) / 2 = Cos(60)
Sin(45) = (√2) / 2 = Cos(45)
Sin(60) = (√3) / 2 = Cos(30)

Various Formulae

Sin2(x) = Sin(x) * sin(x)
Sin(x2) = Sin(x * x)
Tan(x) = Sin(x) / Cos(x)
Sin2(x) + Cos2(x) = 1
Sin(x) = Cos(90 - x)
Cos(x) = Sin(90 - x)

A / Sin(a) = C / Sin(c) = C / Sin(c)
a2 = b2 + c2 - 2bc * Cos (A)

Note:
± = ± → + = + → - = -
± = ∓; → + = - → - = +

Sin(a ± b) = Sin(a) * Cos(b) ± Cos(a) * Sin(b)
Sin(a ± b) = Cos(a) * Cos(b) ∓ Sin(a) * Sin(b)

Sin(2a) = 2Sin(a) * Cos(a)
Cos(2a) = Cos2(a) - Sin2(a)

Sin2(a) = ( 1 - Cos(2a) ) / 2
Cos2(a) = ( 1 + Cos(2a) ) / 2

Csc(x) = 1 / Sin(x)
Cot(x) = 1 / Tan(x) = Cos(x) / Sin(x)
Sec(x) = 1 / Cos(x)
Sec2(x) = 1 / Cos2(x)

Quadratics

Turning Point

The equation dor the turning point x value is: -b / 2a, after that y can be derived.

Complete the Square

The completed square looks like this:
y = a(x + dx)2 + dy
a is the shape, a negative value indicates a n like shape where a positive value indicates a u like shape and if a is 0 the shape is a flat line.
dx is the negative displacement of x.
dy is the displacement of y.

Formulae

To convert a general quadratic to the completed square, use the following formulae:
y = ax2 + bx + c → a(x + b / 2a)2 - b2 / 4a + c