Access Point #: MAFS.912.G-CO.4.AP.12d (Archived Access Point)

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Bisect an angle.


Essential Understandings


  • When given an angle, use manipulatives (e.g., compass, protractor, reflective devices, paper folding, dynamic geometric software, etc.) to bisect the given angle.

    Image of a bisected angle.
  • Place point of compass on the vertex of begin mathsize 12px style angle B A C end style (point A).
  • Stretch the compass to any length so long as it stays ON the angle.
  • Swing an arc so the pencil crosses both sides of begin mathsize 12px style angle B A C end style. This will create two intersection points with the sides (rays) of the angle.
  • Place the compass point on one of these new intersection points on the sides of begin mathsize 12px style angle B A C end style.
  • Without changing the width of the compass, place the point of the compass on the other intersection point on the side of the angle and make the same arc. The two small arcs in the interior of the angle should be crossing.
  • Connect the point where the two small arcs cross to the vertex A of the angle.
  • The two new angles created are of equal measure (and are each ½ the measure of begin mathsize 12px style angle B A C end style).
  • Bisect means to divide into two equal parts.

    Image of a bisected angle showing two equal parts labeled.
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Number: MAFS.912.G-CO.4.AP.12d Category: Access Points
Date Adopted or Revised: 07/14 Cluster: Make geometric constructions. (Geometry - Supporting 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.4.12: Make formal geometric constructions with a variety of tools and methods (compass and straightedge, string, reflective devices, paper folding, dynamic geometric software, etc.). Copying a segment; copying an angle; bisecting a segment; bisecting an angle; constructing perpendicular lines, including the perpendicular bisector of a line segment; and constructing a line parallel to a given line through a point not on the line.

Geometry - Fluency Recommendations

Fluency with the use of construction tools, physical and computational, helps students draft a model of a geometric phenomenon and can lead to conjectures and proofs.

Related Courses

Name Description
1200400: Foundational Skills in Mathematics 9-12
1206310: Geometry
1206320: Geometry Honors
0101340: Three-Dimensional Studio Art 2
0101350: Three-Dimensional Studio Art 3 Honors
0104340: Drawing 1
0104350: Drawing 2
0104360: Drawing 3 Honors
0104370: Painting 1
0104380: Painting 2
0104390: Painting 3 Honors
0109310: Portfolio Development: Drawing-Honors
0109320: Portfolio Development: Two-Dimensional Design Honors
0109330: Portfolio Development: Three-Dimensional Design Honors
0114800: Florida's Preinternational Baccalaureate Art 1
0114810: Florida's Preinternational Baccalaureate Art 2
7912070: Access Mathematics for Liberal Arts
0101355: Creating Two-Dimensional Art
0101365: Creating Three-Dimensional Art
1206315: Geometry for Credit Recovery
1207300: Liberal Arts Mathematics 1
7912065: Access Geometry
0104335: Drawing 1
7967015: Access Drawing 1
0104412: Figure Drawing 2

Related Resources

Element Cards

Name Description
High School Math Element Cards:

Element Cards are available to assist in planning for instruction. They are designed to promote understanding of how students move toward the academic standards. Element Cards contain one or more access points, essential understandings, suggested instructional strategies and suggested supports.