Y7MA4_Lines and angles_10_01_2012

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Lines and angles : 

Lines and angles Lesson objective: To be able: to draw lines and angles to estimate the size of angles to identify types of angle. [Level 4/5] Key words: parallel perpendicular right acute obtuse Starter: Sketch a pair of parallel lines Perpendicular lines

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Parallel lines – NEVER meet Random lines – Intersect at a point X Perpendicular lines – Intersect at right angles Draw the following lines and write down some names for them. X

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What is ANGLE ??? An angle is formed when two lines meet and is measured in degrees. We use a little circle ° following the number to mean degrees. For example 32° means 32 degrees. 32 °

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What is the size and the name of this angle? 90° - Right angle

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What is the size and the name of this angle? 180° - Half turn

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What is the size and the name of this angle? 360° - Full turn

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90° - Right angle 180° - Half turn 360° - Full turn IMPORTANT ANGLES TO REMEMBER

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What is the size and the name of this angle? Less than 90° - Acute angle

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All the angles which are less than 90° are ACUTE ANGLES

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What is the size and the name of this angle? Between 90° and 180°- Obtuse angle

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All the angles which are between 90° and 180° are OBTUSE ANGLES

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What is the size and the name of this angle? Between 180° and 360°- Reflex angle

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All the angles which are between 180° and 360° are REFLEX ANGLES

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Summary Acute Angle: less than 90° Obtuse Angle: more than 90° but less than 180° Reflex Angle: more than 180° but less than 360°

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AB = AC OR AB = CD and AD = BC AB is parallel to CD or AB//CD AD is parallel to BC or AD//BC EXAMPLE

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Write down which of the angles below are acute, which are obtuse and which are reflex. Estimate the size of each one. Work in pairs….

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a. BC = DE = CD b. BC = DE c. BC = CD Work in pairs…. d. BD = CE

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Identify any type of angles Obtuse angles Right angles Work in pairs….

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Identify any type of angles Obtuse angle Obtuse angles Right angles Acute angles Work in pairs….

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http://mathspool2.co.uk/#/grade-c-2011/4544717033 PLENARY Easy angles => Type of angles

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The protractor helps us to measure the size of an angle. Later on we learn how to use it.

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http://www.mathplayground.com/alienangles.html Estimate angles-NOT for this lesson