**Similar shapes** have matching corresponding angles and corresponding sides which are in the same **ratio**.

In these two triangles, the angles match and you will notice that the second triangle has sides which are double the length of the sides of the first triangle.

The **ratio **of the bases is 3:6, which simplifies like a fraction to 1:2.

The ratio of the heights is 7:14, which simplifies like a fraction to 1:2.

**Example**

These two rectangles are similar.

Find the missing length.

**Answer**

The** ratio of the bases is 4:8**, which simplifies to **1:2.**

The big rectangle's sides are 2 times the matching sides of the small rectangle.

The missing side is 2 × 5 = **10 cm**.

Let's have a go at the questions now.