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Line 68: − + − 1) "The sum of interior opposite angles of cyclic quadrilateral is 180 degrees". − 2) "In a cyclic quadrilateral the exterior angle is equal to interior opposite angle". === − + − Coloured paper, pair if scissors, sketch pen, carbon paper, geometry box − # Draw a circle of any radius on a coloured paper and cut it. − # Paste the circle cut out on a rectangular sheet of paper. − # By paper folding get chords AB, BC, CD and DA in order. − # Draw AB, BC, CD & DA. A cyclic quadrilateral ABCD is obtained. − # Make a replica of cyclic quadrilateral ABCD using carbon paper. − # Cut the replica into 4 parts such that each part contains one angle . − # Draw a straight line on a paper. − # Place angle BAD and angle BCD adjacent to each other on the straight line.Write the observation. − # Place angle ABC and angle ADC adjacent to each other on the straight line . Write the observation. − # Produce AB to form a ray AE such that exterior angle CBE is formed. − # Make a replica of angle ADC and place it on angle CBE . Write the observation. − Observations : − 1) angle BAD and angle BCD , when placed adjacent to each other on a straight line, completely cover the straight angle. This means their sum is 180 degrees. − 2) angle ABC and angle ADC , when placed adjacent to each other on a straight line, completely cover the straight angle. This means their sum is 180 degrees. − 3) The replica of angle ADC completely covers angle CBE. − RESULT: a)The sum of either pair of opposite angle of a cyclic quadrilateral is 180 degrees. − − b)In a cyclic quadrilateral, the exterior angle is equal to interior opposite angle.
→Notes for teachers
===Learning objectives===
===Learning objectives===
===Notes for teachers===
===Notes for teachers===
===Activity No #1.By paper folding, cutting and pasting verify that
===Activity No ===
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|<div style="width:150px;border:none; border-radius:10px;box-shadow: 5px 5px 5px #888888; background:#f5f5f5; vertical-align:top; text-align:center; padding:5px;">
|<div style="width:150px;border:none; border-radius:10px;box-shadow: 5px 5px 5px #888888; background:#f5f5f5; vertical-align:top; text-align:center; padding:5px;">
''[http://www.karnatakaeducation.org.in/?q=node/305 Click to Comment]''</div>
''[http://www.karnatakaeducation.org.in/?q=node/305 Click to Comment]''</div>
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*Estimated Time :40 minutes
*Estimated Time :
*Materials/ Resources needed:
*Materials/ Resources needed:
*Prerequisites/Instructions, if any
*Prerequisites/Instructions, if any
*Multimedia resources
*Multimedia resources
*Website interactives/ links/ / Geogebra Applets
*Website interactives/ links/ / Geogebra Applets
*Process:
*Process:
*Developmental Questions;
*Developmental Questions;
*Evaluation
*Evaluation