# Maths Non-Calc. Facts & Formulas

Some facts and formulas for shapes and lines.

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• Created by: Melina
• Created on: 06-06-10 13:04

## LCM and HCF

LCM - Lowest Common Multiple

• Smallest Number that
• Divides by
• All Numbers in question

HCF - Highest Common Factor

• Biggest Number that
• Divides into
• All Numbers in question
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## Recurring Decimal to Fraction

Step-by-Step Example:

• Call your original recurring decimal, x
• x = 0.232323...
• Times by 100
• 100x = 23.232323...
• Minus x from 100x
• 99x = 23
• To get x, devide both sides by 99
• x = 23/99
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## Sine & Cosine Rules

Cosine Rule: a² = b² + c² - 2bc cos C

• Used with visible 3 sides, no angles OR
• 2 sides, 1 enclosed angle
• ﻿

Sine Rule: a/sinA = b/sinB = c/sinC

• Used with visible 2 angles, 1 side OR
• 2 sides, 1 closed angle
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## Areas and Volumes

Trapezium

• Area = ½(a + b)h

Parallelogram

• Area = b x h

Cylinder

• Surface Area = 2πr(l+r)
• Area of curved surface = πrl
• Volume = πr²l
﻿﻿
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