A triangle has corners points A, B, and C. Side AB has a length of 3 . The distance between the intersection of point A's angle bisector with side BC and point B is 1 . If side AC has a length of 4 , what is the length of side BC?

2 Answers
Jun 11, 2016

7/3

Explanation:

DrawnDrawn

Given

  • In Delta ABC, AB =3,AC=4
  • AD",the bisector of " /_BAC,"intersects BC at D" and BD=1
  • We are to find out the length of BC

Construction

  • CE" is drawn parallel to DA, it intersects produced BA at E"

Now

  • DA||CE,AC -"transversal"-> /_ DAC="alternate"/_ ACE

  • DA||CE,BE-"transversal"-> /_ BAD="corresponding"/_ AEC

  • But /_BAD =/_DAC,"AD being bisector of " /_BAC

  • :.In" "DeltaACE,/_ACE=/_AEC=>AC=AE=4

  • " Now "DA||CE->"BD"/"DC"="BA"/"AE"=3/4

  • "BD"/"DC"=3/4=>1/"DC"=3/4=>DC=4/3

  • BC=BD +DC=1+4/3=7/3

Jun 11, 2016

bar(BC)=7/3

Explanation:

According to the figure attached, using sinus law we have

1/sin(alpha)=3/sin(beta)
x/sin(alpha)=4/sin(pi-beta)=4/sin(beta)

so we have

{ (sin(beta)=3 sin(alpha)), (x sin(beta) =4 sin(alpha)) :}

Then we obtain x = 4/3 and bar(BC)=1+x=7/3

enter image source here