Question

20. Find the length of BC in the figure below.
A- 12
BC ?
E - 16
D - 8

Answer 1

Explanation:

First, we split the triangles into two

Δ ADC and ΔAEB

Then we look for similar things

First, both triangles have ∠A which makes the angles equal

Then we can see that side BE is // to line CD

That makes ∠D =∠E and ∠B = ∠C

Now we can have a ratio of the sides

AE/AD = AB/AC = EB/DC

AB/AC = AE/AD

12/12 + x = 16/24

Cross multiply

12 × 3 = 2 (12 + x)

36 = 24 + 2x

36 - 24 = 2x

12 = 2x

x = 6

BC = 6cm