In the diagram, ∆PQR is similar to ∆PWY. WY||QR, |QR| = 15 cm, |WY| = 6 cm and |WP| = 4 cm.
Find |WQ|.
The ratio of the corresponding sides of the larger and smaller ∆s are the same.
= =
|PQ| = |PW| + |WQ|
|WQ| = |PQ| - |PW|
Use the known sides to find the |PQ|
=
=
Cross multiply.
|PQ| x 6 cm = 15 cm x 4 cm
Divide both sides by 6 cm
|PQ| = = 10 cm
|WQ| = |PQ| - |PW|
|WQ| = 10 cm - 4 cm
|WQ| = 6 cm
