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Line 98: − + − ### Ask them to see if there's any relationship between the parameters. they've measured. + − # Question them if there is any relationship between the two segment lengths and the measures of the two pairs of angles. + − ## Ask them why these relationships are true across different constructions. + − Line 121:
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Quadrilaterals-Activity-Mid-point theorem (view source)
Revision as of 13:41, 7 November 2019
, 13:41, 7 November 2019→Evaluation at the end of the activity
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# Ask them to see if there is any relationship between the two segment lengths and the measures of the two pairs of angles.
# Ask them if these relationships are true across different constructions. Can they look at the observations and state it as a rule or a statement
# Tell students that we will use properties of parallel lines and parallelogram for this proof (to help them get into the thinking about the process of deduction, required in proving theorems).
# Prove the theorem, using [[:File:Mid-point theorem 2.ggb|Mid-point theorem2.ggb]] (students can follow the demonstration through Geogebra and also write the steps in their book, relating to the triangle that they have drawn)
# Prove the theorem, using [[:File:Mid-point theorem 2.ggb|Mid-point theorem2.ggb]]
## In △ ABC, D and E are the midpoints of sides AB and AC respectively. D and E are joined.
## In △ ABC, D and E are the midpoints of sides AB and AC respectively. D and E are joined.
## Given: AD = DB and AE = EC. To Prove: DE ∥∥ BC and DE = 1/2 BC.
## Given: AD = DB and AE = EC. To Prove: DE ∥∥ BC and DE = 1/2 BC.
# By the properties of parallelogram, we have DF ∥∥ BC DF = BC DE ∥∥ BC.
# By the properties of parallelogram, we have DF ∥∥ BC DF = BC DE ∥∥ BC.
## DE = 1/2BC (DE = EF by construction)
## DE = 1/2BC (DE = EF by construction)
=== Evaluation at the end of the activity ===
=== Evaluation at the end of the activity ===
# Would this theorem apply for right angled and obtuse-angled triangles?
# Would this theorem apply for right angled and obtuse-angled triangles?
[[Category:Quadrilaterals]]
[[Category:Quadrilaterals]]
[[Category:Class 9]]
[[Category:Class 9]]