Question

if AC equals 12, DC = 7, DE = 5 and the perimeter of triangle ABC is 30 what is the perimeter of triangle DEC?

Answer 1

Perimeter of DEC is 17.5

Here, we want to calculate the perimeter of the triangle DEC

From the question, we have that the triangles are similar

If two triangles are similar, the ratio of their corresponding sides are equal

Let us get the lengths of the similar sides

The similar sides here are AC and DC

The ratio of this two is 7 to 12

So, the perimeter of the smaller triangle will be;

$\frac{7}{12}\times30\text{ = 17.5}$