In triangle PQR, S is on PQ and T is on PR with ST parallel to QR. $PS : SQ = 2 : 3$ and $QR = 20$ cm. What is ST?

Explanation

1. 01

   $ST \parallel QR$, so triangle PST is similar to triangle PQR.

2. 02

   $PS : PQ = 2 : (2 + 3) = 2 : 5$.

3. 03

   ST = $20 \times \frac{2}{5} = 8$ cm.