- Coordinates for 3D CAD Modeling
- Geometric Entities
- 4.1 Manually Bisecting a Line or Circular Arc
- 4.2 Drawing Tangents to Two Circles
- 4.3 Drawing an Arc Tangent to a Line or Arc and Through a Point
- 4.4 Bisecting an Angle
- 4.5 Drawing a Line through a Point and Parallel to a Line
- 4.6 Drawing a Triangle with Sides Given
- 4.7 Drawing a Right Triangle with Hypotenuse and One Side Given
- 4.8 Laying Out an Angle
- 4.9 Drawing an Equilateral Triangle
- 4.10 Polygons
- 4.11 Drawing a Regular Pentagon
- 4.12 Drawing a Hexagon
- 4.13 Ellipses
- 4.14 Spline Curves
- 4.15 Geometric Relationships
- 4.16 Solid Primitives
- 4.17 Recognizing Symmetry
- 4.18 Extruded Forms
- 4.19 Revolved Forms
- 4.20 Irregular Surfaces
- 4.21 User Coordinate Systems
- 4.22 Transformations
- Key Words
- Chapter Summary
- Skills Summary
- Review Questions
- Chapter Exercises

## 4.11 Drawing a Regular Pentagon

**Dividers Method:** Divide the circumference of the circumscribed circle into five equal parts with the dividers, and join the points with straight lines (Figure 4.35a).

**4.35** Drawing a Pentagon

**Geometric Method:**

**Step 1.**Bisect radius*OD*at*C*(Figure 4.35b).**Step 2.**Use*C*as the center and*CA*as the radius to lightly draw arc*AE.*With*A*as center and*AE*as radius, draw arc*EB*(Figure 4.35c).**Step 3.**Draw line*AB*, then measure off distances*AB*around the circumference of the circle. Draw the sides of the pentagon through these points (Figure 4.35d).