In Fig. 7.137, AB || QR. Find the length of PB.
InΔPAB andΔPQR Δ
∠ APB = ∠ QPR (common angle)
∠ PAB= ∠ PQR ( corresponding angles)
∠ PBA = ∠ PRQ (corresponding angles)
Hence, Δ PAB andΔPQR are similar by AAA criteria.
So, ( Corresponding angles of similar triangles)