Geometry for Elementary School/Copying an angle
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In this chapter, we will show how to copy an angle to other angle .
The construction is based on Book I, proposition 23.
The construction[edit | edit source]
- Draw a line between A and C and get .
- Copy the triangle and get
Claim[edit | edit source]
The angles and are equal.
Proof[edit | edit source]
- The triangles and congruence.
- Therefore the angles of the triangles equal.
- Hence, and are equal.
Note that any two points on the rays can be used to create a triangle.