Question

If AC =15 how long is ED? Help me :(

Answer 1

ED=7.5

Explanation:

ΔABC is similar to ΔDEB (they share ∠B, and ∠C=∠D and ∠A=∠E because corresponding angles), so their sides are in ratio:

ED/AC=BD/BC

We can see that BC is twice BD (marked), so we know BD/BC=0.5

ED/AC=BD/BC

ED/15=0.5

ED=7.5

Answer 2

7.5

Explanation:

Using similar triangles.