1. Geometry Chapter 11 Review

2. Parallelogram A = bh Base Height

3. Triangle A = ½ bh Base Height Imagine dropping a rock from the highest point down to the base to find the height.

4. Rhombus A = ½ d 1 d 2 Take ½ of whichever diagonal is easier than multiply.

5. Area of a Trapezoid The area of a trapezoid equals half the product of height and the sum of the bases. A = ½h(b 1 + b 2 ) Area = ½(6)(8 + 12) = 60 square units b1b1 h b2b2 8 12 6

6. Easy method : Find m first A = ½h(b 1 + b 2 ) m is the median length of the trapezoid m = ½ (b 1 + b 2 ) So, more simply: A = hm It is the average of the bases

7. Area of a Regular Polygon A = ½ a p apothem perimeter. apothem

8. Circle Formulas Area = πr² r d Circumference = 2πr = d π

9. Area of a Sector Formula m 360 πr2πr2 Area of a sector = measure of the central angle or arc The fraction of the circle! The area of the entire circle!.

10. Arc Length Formula m 360 2πr2πr Arc Length = measure of the central angle or arc The fraction of the circle! The circumference of the entire circle!.

11. What to ask yourself when comparing the areas of a triangle!!! 1) Do the triangles have the same height? If yes, the ratio of the areas is the ratio of the bases. 2) Do the triangles have the same base? If yes, the ratio of the areas is the ratio of the heights. 3) Are the figures similar? If yes, the ratio of the areas is the square of the scale factor.

12. Suppose a point P of XY is picked at random. Then: probability that P is on X Q Y

13. Suppose a point P of region A is picked at random. Then: B A A B probability that P is in region B =

14. HW