This is a triangle
To find the area, count the side (which is 5)
You can see that the peak opposite of the side is 7 units in length, that is the height
The formula for the area of the triangle is
A = (b * h)/2
b = 5
h = 7
A = (5 * 7)/2
A = 35/2
A = 17.5
Hope this helps