## precal one year ago Isosceles Triangle Problem

1. precal

2. precal

@Loser66

3. anonymous

$$\Delta BDE$$ and $$\Delta CDF$$ are similar. You know this because angles $$\angle ABC$$ and $$\angle ACB$$ are congruent, and they are both right triangles, so the remaining angles $$\angle BDE$$ and $$\angle CDF$$ must also be congruent.

4. precal

Did I mention I can't use a calculator at all?

5. precal

so what do I do now?

6. Nnesha

i don't think we need a calculator for this question hmmmm according to what he/she said: we can set up a proportion: i was looking at this link ( http://www.mathplanet.com/education/geometry/similarity/triangles ) : if the triangles are similar then their corresponding sides are proportional

7. Nnesha

|dw:1444252141871:dw| we can separate both right triangles |dw:1444252199454:dw| $\huge\rm \frac{ BD }{ CD } = \frac{ DE }{ DF}$ given DE : DF  5:7 and bec BD/CD is equal to DE/DF we can say the ratio of BD :CD is also 5:7

8. Nnesha

make sense or not ?? hmmmm

9. Nnesha

BD : CD = 5 :7 BD/CD = 5/7 and we know BD + CD = 48 suppose BD = 5y and CD = 7 y |dw:1444254518735:dw|