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Activity-construction of angles (view source)
Revision as of 09:12, 3 November 2019
, 09:12, 3 November 2019no edit summary
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== Construction of an angle with measure 22.5∘ ==
== Construction of an angle with measure 22.5∘ ==
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===Evaluation at the end of the activity===
===Evaluation at the end of the activity===
−# Ask students, what are the other angles that can drawn in the same construction. (Hint, there are new angles created, which are adjacent/ complementary / supplementary to the angles we have discussed. For eg. we get an angle with measure 135 (by considering one 90 and one 45 angles adjacent to each other).
+# Ask students, what are the other angles that can drawn in the same construction. (Hint, there are new angles created, which are adjacent/ complementary / supplementary to the angles we have discussed. For eg. we get an angle with measure 135 (by considering one 90 and one 45 angles adjacent to each other).
+== Construction of an angle with measure 60∘ ==
+===Objectives===
+Understand construction of an an angle with measure 60∘. Problem Class 9.
+=== Estimated Time ===
+One period
+===Prerequisites/Instructions, prior preparations, if any===
+Introduction to Angles
+===Materials/ Resources needed===
+Geogebra file Construction of angle with measure 60∘
+===Process (How to do the activity)===
+# Explain the process of constructing an angle with measure 60∘ (without using a protractor). Students can follow and do the construction in their books
+## Draw a circle with centre as point A, and with any given radius. Select a point B on the circle, and with the same radius, construct another circle.
+## Mark the intersection points of the two circles, C and D
+## Draw line segment AC.
+## Measure ∡BAC, it will be 60∘
+## Draw line segments AB and BC.
+## Measure ∡ABC, ∡ACB.
+## This process will create two more angles. Measure both angles. They will be 60∘ each
+## Why does this process work? (Explanation - We have constructed a triangle whose all sides are congruent to one another. This is an equilateral triangle. Equilateral triangle also is an 'equiangular' triangle, where all angles are congruent to one another. The sum of measures of angles of a triangle is 180∘, and each angle is 60∘)
+# You can use the 'Play - Construction protocol' to show the above steps one by one. But do this after constructing the equilateral triangle using Geogebra.
+===Evaluation at the end of the activity===
+# Ask students, what are the other angles that can drawn in the same construction. (Hint, there are new angles created, which are adjacent/ complementary / supplementary to the angles we have discussed. For eg. we get an angle with measure 120 (supplement of ∡ABC) if we extend segment AB beyond point B.
[[Category:Lines and Angles]]
[[Category:Lines and Angles]]
[[Category:Class 9]]
[[Category:Class 9]]