Geometry: An Interactive Journey to Mastery

(Greg DeLong) #1
F௘ͽ Figure S.26.4 shows how to draw an equilateral triangle
with a given segment as one of its sides.
To draw a hexagon, draw an equilateral triangle.
And then draw a second equilateral triangle on one
of its sides.
Do this six times to construct a hexagon.
௘6HHFigure S.26.5௘ͽ


  1. Draw a circle with the vertex of the angle its center. This circle
    intersects the rays at two points, A and B ௘6HHFigure S.26.6௘ͽ
    Draw circles each of radius AB with centers at A and B.
    Let P be one of their points of intersection. Also, call the vertex of the angle O.
    Then, the line OPHJJG is the angle bisector of ‘AOB. ௘6HHFigure S.26.7௘ͽ
    To see why, notice that OA = OBE\RXU¿UVWVWHSDQGAP = BP by our second step.
    So, triangles OAP and OBP are similar by SSS and, therefore, ‘#‘AOP BOP.

  2. 'UDZWKHSHUSHQGLFXODUELVHFWRURIHDFKVLGHRIWKHWULDQJOH²E\WKHPHWKRG
    shown in the lesson. We know from Lesson 12 that these three line segments
    meet at a common point P that is the center of the circle that passes through
    each vertex of the triangle. Set one point of the compass at P and the other at
    one corner of the triangle, and draw the circle of this radius with center P.
    ͼ௘:DVLWQHFHVVDU\WRFRQVWUXFWDOOthreeSHUSHQGLFXODUELVHFWRUV"௘ͽ


r

rr

Figure S.26.4

A


B


Figure S.26.6

A
O P
B
Figure S.26.7

Figure S.26.5
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