Question

What is the area of this triangle.

Answer 1

Answer:

13 square units

Step-by-step explanation:

You could calculate the length of each side using Pythagorean theorem, then use Heron's formula to find the area.  But there's an easier way: find the area of the rectangle that contains the triangle, and subtract the areas of the smaller triangles in the corners.

The area of the rectangle is 4 × 7 = 28.

The area of the upper left triangle is ½(2)(4) = 4.

The area of the upper right triangle is ½(3)(5) = 7.5.

The area of the lower right triangle is ½(1)(7) = 3.5.

So the area of the triangle is:

28 − 4 − 7.5 − 3.5 = 13