Look at Δ *ABD* in Figure 1* BC *is drawn through

*B*parallel to

*and another line*AD

*is drawn through*DC

*D*parallel to

*, then you will have formed a parallelogram.*AB

*is now a diagonal in this parallelogram. Because a diagonal divides a parallelogram into two congruent triangles, the area of Δ*BD

*ABD*is exactly half the area of

*ABCD.*

**Figure 1 **Area of a triangle is half the area of the associated parallelogram.

## Finding the Area

Because *A* _{parallelogram} = *bh*, then

## Finding the Perimeter

In Δ *ABD* (Figure 1

**Example 1:** Find the perimeter and area for the triangles in Figures

**Figure 2 **Finding perimeters and areas of triangles.

**Example 2:** If the area of a triangle is 64 cm^{2} and it has a height of 16 cm, find the length of its base.

Multiply both sides by 2.

The triangle will have a base of 8 centimeters.