The area is the space inside the shape.
To do it using the area tool, click on the icon with the angle and scroll down until you find the tool labeled "Area" and then click on the triangle.

To find the area of scalene triangles like this one without using the area tool, you can't just find the length of two of the sides and use the formula for the area of triangles. What you have to do is make three other triangles all with one 90 degree angle. Find the length of the two outer sides of the triangles that is not the one in the middle. After that, find the area of those triangles. As you can see, the triangles have made a square. Find the area of the square and then subtract the area of the triangles from the area of the square to get the area of the middle triangle. Below is how to do it step by step.