Access Point #: MAFS.912.G-CO.3.AP.10a (Archived Access Point)


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Measure the angles and sides of equilateral, isosceles, and scalene triangles to establish facts about triangles.

Clarifications:

Essential Understandings

Concrete:

  • Given an angle measure, draw an angle.
  • Recognize that a triangle consists of three angles that total 180 degrees.
  • Recognize the measures of base angles of an isosceles triangle are equal (same).
  • Use paper folding to demonstrate angle relationships.
  • Use a protractor to show that angles are supplementary (equals 180 degrees).
  • Use a protractor to measure interior and exterior angles of a triangle.
  • Recognize that the angle measure of a straight line is 180 degrees.
  • Construct a triangle.
  • Construct a triangle given angle measurements.
  • Given a paper triangle, tear the angles off and place them together to create a straight angle.
  • Given a triangle, draw the exterior angles.
  • Measure the length of a line segment. Construct the median of the sides of a triangle.
Representation:
  • Match or identify angle measurements.
  • Match or label angle measurements.
  • Given an angle measurement, determine the interior or exterior angle supplementary to it.
  • Find the sum and difference of pairs of interior angles in a triangle.
  • Use appropriate tools as needed.
  • Understand the following concepts and vocabulary: acute, obtuse, right, straight line, interior angles, exterior angles, perpendicular bisector, equal distance, angle sum theorem, supplementary angles, base angles, isosceles triangles, midpoints, median, congruent, centroid.
  • Given a triangle, determine the median of each side.
  • Identify the centroid of the triangle, given the median of each side.

Number: MAFS.912.G-CO.3.AP.10a Category: Access Points
Date Adopted or Revised: 07/14 Cluster: Prove geometric theorems. (Geometry - Major Cluster)

Clusters should not be sorted from Major to Supporting and then taught in that order. To do so would strip the coherence of the mathematical ideas and miss the opportunity to enhance the major work of the grade with the supporting clusters.

Related Standards

Name Description
MAFS.912.G-CO.3.10: Prove theorems about triangles; use theorems about triangles to solve problems. Theorems include: measures of interior angles of a triangle sum to 180°; triangle inequality theorem; base angles of isosceles triangles are congruent; the segment joining midpoints of two sides of a triangle is parallel to the third side and half the length; the medians of a triangle meet at a point.



Related Courses

Name Description
1200400: Foundational Skills in Mathematics 9-12
1206310: Geometry
1206320: Geometry Honors
1206315: Geometry for Credit Recovery
7912065: Access Geometry