SIMILAR TRIANGLES Powerpoint for Grade 9

Lesson PPT

1. SIMILAR FIGURES SUBJECT TEACHER: IVY EUNICE F. FEUDO 9TH GRADE

2. two polygons with the same shape, but not the same size. Similar Polygons

3. SUBJECT TEACHER: IVY EUNICE F. FEUDO

4. Properties of similar polygons: 1. The corresponding angles are equal/congruent. 2. The ratio of the corresponding sides is the same for all sides/ proportional.

5. Example 1. 1. Name the corresponding angles. 2. Name the corresponding sides. 3. Determine the scale factor of two similar triangles.

6. Example 2.

7. EXAMPLE 3.

8. Juliet wants to make a new sail for her father's sailboat. She finds the old sketch that she used to make the first sail and she redraws the sketch so that she can make the new sail. Her two figures are similar.

9. How can Juliet use a proportion to decide the length of KJ in inches?

10. EXAMPLE 1 .

11. Applying the Pythagorean Theorem

12. A 15 foot ladder leans up against a building. The foot of the ladder is 5 feet from the base of the building. How high up the wall, to the nearest foot does the ladder reach? Draw a picture: 15 5 x

13. Solving the problem a 2 + b 2 = c 2 Write formula x 2 + 5 2 = 15 2 Substitute in x 2 + 25 = 225 Solve for x - 25 -25 x 2 = 200 x = 14.142135 Check: How am I to leave my answer? The ladder reaches 14 feet up the wall.

14. Tim rode 8 miles due north, then 3 miles due east. How far, to the nearest mile, is Tim from where he started? Draw a picture: 8 3 x

15. Solve the problem a 2 + b 2 = c 2 8 2 + 3 2 = c 2 64 + 9 = c 2 73 = c 2 Remember: How am I suppose to leave my answer? C = 8.5440037 Tim is 9 miles from where he started.

16. Isosceles Right Triangle theorem: The length of hypotenuse is equal to the product of the length of the leg and