Similar triangles: find a missing side
Find the scale factor from the matching sides, then multiply.
See worked examples
Two triangles are similar. In the small one, two matching sides are 12 cm and 18 cm. In the large one, the side matching 12 cm is 24 cm. How long is the side matching 18 cm?
Answer: 36 cm
Two triangles are similar. In the small one, two matching sides are 4 cm and 16 cm. In the large one, the side matching 4 cm is 16 cm. How long is the side matching 16 cm?
Answer: 64 cm
Two triangles are similar. In the small one, two matching sides are 6 cm and 22 cm. In the large one, the side matching 6 cm is 12 cm. How long is the side matching 22 cm?
Answer: 44 cm
Tip: Find the scale factor from the matching sides, then multiply.
Practise without limits
Members practise as much as they like, every day, and get the printable packs and lessons too.