# Formula Tips

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• Created by: 24122002
• Created on: 10-11-18 11:41

## Area Triangle Rule

Area = 1/2absin(c)

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## Sine Triangle Rule

a / Sin A  =  b / Sin B  =  c / Sin C

For Example:

b / Sin B  =  c / Sin C

15 / Sin (70) = c / Sin(83)

c = 15 / Sin(70) x Sin(83)

c = 15.84

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## Cosine Rule

a (squared) = b (squared) + c (squared) - 2bc CosA

For Example:

a (squared) = 5 (squared) + 8 (squared) - 2 x 5 x 8 x Cos(120)

= 129

a = 129 (square rooted) = 11.35

= 11.35cm

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## Letter key

CAPITAL LETTERS = Angles

lower case = Length

LETTERS ARE INTERCHANGABLE !!!

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## SOHCAHTOA

O            =    SINE

S     H

A           =   COSINE

C     H

O         =   TANGENT

T      A

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## Sine Pairs

Sin (30) = 1 / 2

Sin(45)  = 2 (squared rooted) / 2

Sin (60) = 3 (squared rooted) / 2

Sin(90)  = 1

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## Cosine Pairs

Cos(30) = 3 (square rooted) / 2

Cos(45) = 2 (square rooted) /  2

Cos(60) = 1/2

Cos(90) = 0

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## Tangent Pairs

Tan(30) = 3 (square rooted) / 3

Tan(45) = 1

Tan(60) = 3 (Square rooted)

Tan(90) = MATHS ERROR

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