After completing this chapter, students will be able to:

- find the area of triangle and quadrilateral using trigonometric formula.
- find the height and distance by using trigonometry.

The area of a polygon is the number of square units inside that polygon.The area is 2-dimensional like a carpet or an area rug. A triangle is a three-sided polygon.

The angle made by the line through his eyes and top of the tree with the line parallel to the ground is called the angle of elevation. The angle formed by the line joining the object and the eye of the observer with the horizon is called the angle of depression.