What is the area of the triangle?

Answer:
[tex]10\:\mathrm{units^2}[/tex]
Step-by-step explanation:
The area of a triangle can be given as [tex]\frac{1}{2}\cdot b \cdot h[/tex]. Notice that a base of the triangle is given as 4 units, and the height is marked as 5 units. We know that the segment marked as 5 units is the height of the triangle because it forms a [tex]90^{\circ}[/tex] with the segment marked as 4 units and meets a vertex of the triangle.
Therefore, the area of the triangle is:
[tex]\frac{1}{2}\cdot 4 \cdot 5 = \fbox{$10$}[/tex].