Topic: Geometry -- Area

Today we talked about solving area problems for rectangles and triangles. There are two strategies:

• Direct way: when using this method, you need to find out the lengths of two sides (for rectangle) or base and height (for triangle)
• Indirect way: you can use the ratio between areas of related shapes, to find out the area of one shape from another (with known area).

When you find it is difficult (or impossible) to calculate the length of sides or height, try the indirect method.

Homework

1. ABCD is a rectangle. E and F are both mid-point of the corresponding edge. What is the ratio between the area of ABCD and the area of AEF?

2. A and D are right angles, and the numbers show the areas of two of the triangles.

What is the area of ABCD?