A vertex angle is an angle found in all geometric figures in which two line segments become connected forming an angle that is measured from the inside walls of the two connecting
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1. Find the slopes of the lines that contains each segment. The slope of a line is calculated by dividing the change in ycoordinates by the change in xcoordinates: slope = (y2 
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The letter E would be at the vertex. The two lines enclosing the angle E would be ED and EF. Usually, to make it quite clear we would call angle E by the description "angle DEF
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( ′vər′teks ′aŋ·gəl ) (mathematics) In a triangle, the angle opposite the base.
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