Respuesta :
Considering the angle theorems, the appropriate answer to the question is option D. m∠BEC + m∠CED = m∠BED; Angle Addition Postulate
In the diagram, lines BC and ED are parallel and both were intersected by a transversal AE. Thus it can be observed that:
m<ABC = BED = [tex]70^{o}[/tex] (corresponding angle theorem)
But,
m<BEC + m<CED = m<BED (angle addition postulate)
with m<CED = [tex]30^{o}[/tex], and m<BED = [tex]70^{o}[/tex]
So that,
m<BEC + [tex]30^{o}[/tex] = [tex]70^{o}[/tex]
m<BEC = [tex]70^{o}[/tex] - [tex]30^{o}[/tex]
= [tex]40^{o}[/tex]
m<BEC = [tex]40^{o}[/tex]
Since linear pair are two angles that add up to [tex]180^{o}[/tex]. Therefore the required answer is option D.
i.e D. m∠BEC + m∠CED = m∠BED; Angle Addition Postulate
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