# geometry and measures

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• Created by: bio1423
• Created on: 16-06-13 12:18
• Geometry and measures
• metric and imperial units
• metric
• length; 10mm=1cm 100cm=1m 1000m=1km
• weight; 1000mg=1g 1000g=1kg 1000kg=1tonne
• capacity; 1000ml=1litre 100cl=1litre 1000cm3=1litre
• Imperial
• length; 1foot=12inches 1yard=3feet
• weight; 1stone=14pounds 1pound=16ounces
• capacity; 20fluid oz=1pint 8pints =1gallon
• Comparisons between metric and imperial
• length; 2.5cm=1inch 30cm=1foot 1m=39inches 8km=5miles
• weight; 25g=1oz 1kg=2.2lb
• Capacity; 1litre=1.75pints 4.5litres=1gallon
• compound measures
• Average speed=total distance/total time taken
• combination of 2 or more measures
• Time = distance/speed
• Density = mass/volume
• mass=density x volume
• Volume = mass/ density
• Accuracy of measurement
• Discrete measures can be counted
• Continuous measures need a measuring instrument
• are not exact, eg. to nearest kg
• Transformations 1
• changes the position or size of a shape
• Translations
• moves a figure from one place to another
• Vectors used to describe distance & direction
• Vector  written as  a                   b
• a = horizontal movement
• b = vertical movement
• Reflections
• creates an image of an object in other side of mirror line
• mirror line known as axis of reflection
• size and shape not changed
• when describing, write equation of mirror line
• Rotations
• turns a figure through an angle about a fixed point
• fixed point called centre of rotation
• wen describing give centre of rotation, direction, angle of turn
• Transformations 2
• Enlargements
• change size but not shape
• centre of enlargement is point from which enlargement takes place
• scale factor; how many times original lengths increased
• sf>1, shape gets bigger
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