In parallelogram ABCD point K belongs to diagonal
BD
and divides
BD
so that BK:DK=1:4. If ray
AK
meets
BC
at point E, what is the ratio of BE:EC?

Respuesta :

frika

Answer:

[tex]\dfrac{BE}{EC}=\dfrac{1}{3}.[/tex]

Step-by-step explanation:

Consider triangles BKE and DKA. In this triangles:

  • [tex]\angle BKE=\angle DKA[/tex] as vertical angles;
  • [tex]\angle KBE=\angle KDA[/tex] as alternate interior angles (lines BC and AD are parallel and BC is a transversal);
  • [tex]\angle BEK=\angle DAK[/tex] as alternate interior angles (lines BC and AD are parallel and BE is a transversal).

Thus triangles BKE and DKA are similar by AA theorem. Similar triangles have proportional sides lengths:

[tex]\dfrac{BK}{KD}=\dfrac{BE}{AD}\Rightarrow \dfrac{1}{4}=\dfrac{BE}{AD}.[/tex]

Thus, [tex]AD=4BE.[/tex]

Since AD=BC and BC=BE+CE, we have that 4BE=BE+EC, EC=3BE. Hence, the ratio BE to EC is

[tex]\dfrac{BE}{EC}=\dfrac{BE}{3BE}=\dfrac{1}{3}.[/tex]

Ver imagen frika