Journal 7 & 8

1. Journal 7 & 8 By: Maria Jose Diaz-Duran

2. Describe a ratio. Describe a proportion. How are they related? Describe how to solve a proportion. Describe how to check if a proportion is equal • Ratio: compares 2 numbers by division. • Proportion: an equation stating that two ratios are equal They are related since you use proportion to check the ratio so you kind of use both to find the answer. To solve a proportion you need to cross multiply. To see if its equal you need to rearrange it a later on see if it gives you the same answer.

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4. Describe what it means for two polygons to be similar. What is a scale factor? • For two polygons to be similar it means they have the same shape but no necessarily the size Similar polygons: iff their corresponding angles are congruent and their corresponding sides are proportional. • Scale Factor: the ratio of any two corresponding lengths in two similar geometric figures. Describes how much the figure is enlarged or reduced .

5. Examples: http://eigthgrademathmocity2.wikispaces.com/file/view/Dtigers.gif/75151493/Dtigers.gif

6. Describe how to find the scale factor for the perimeter and areas of similar figures • The ratio of the perimeter for similar figure is equal the ratio of similarity. • The ratio of the area is equal to the (Ratio of similarity 2)

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8. Describe how to use similar triangles to make an indirect measurement. • Indirect Measurement: any method to use formulas, similar figures or proportions to measure any object.

9. Examples: http://www.encyclo.co.uk/img/math/indirect_m6%5B1%5D.gif

10. Describe the right triangle altitude proportionality theorem. • The altitude to the hypotenuse of a right triangle forms two triangles that are similar to each other and to the original triangle. So there will be 3 triangles that are similar

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12. Describe the three trigonometric ratios. Explain how they can be used to solve a right triangle. What does it mean to solve a triangle? • Trigonometric ratio: a ratio of two sides of a right triangle.

13. To find an angle you can use the inverse of the trigonometric functions.

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15. Compare an angle of elevation with an angle of depression. How are each used? • Angle of elevation: the angle formed by a horizontal line and a line of sight to a point above the line. • Angle of depression: the angle formed by a horizontal line and a line of sight to a point below the line.

16. Examples: http://rchsbowman.files.wordpress.com/2009/02/021209-0347-geometrynot2.png?w=405&h=184