geometry unit 2 lesson 4 homework

Geometry. Unit 2 Lesson 4: Rotations

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Description

This is the fourth lesson of Unit 2. This curriculum is suitable for a high school geometry class (regular or honors).

In this lesson students will:

• Represent transformations in the coordinate plane.
• Describe transformations as functions that take points in the coordinate plane as inputs and give other points as outputs.
• Use geometric descriptions of rigid motions to transform figures and to predict the effect of a given rigid motion on a given figure.
• Given two figures, use the definition of congruence in terms of rigid motions to decide if they are congruent.

This product contains the following:

• Guided notes
• Homework/Classwork
• Power Point and Keynote slides for presentation of lesson
• Link to extra online practice
• Keys for all of the above

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Geometry (all content)

Unit 1: lines, unit 2: angles, unit 3: shapes, unit 4: triangles, unit 5: quadrilaterals, unit 6: coordinate plane, unit 7: area and perimeter, unit 8: volume and surface area, unit 9: pythagorean theorem, unit 10: transformations, unit 11: congruence, unit 12: similarity, unit 13: trigonometry, unit 14: circles, unit 15: analytic geometry, unit 16: geometric constructions, unit 17: miscellaneous.

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About This Course

Welcome to the Math Medic Geometry course! Here you will find a ready-to-be-taught lesson for every day of the school year, along with expert tips and questioning techniques to help the lesson be successful. Each lesson is designed to be taught in an Experience First, Formalize Later (EFFL) approach, in which students work in small groups on an engaging activity before the teacher formalizes the learning.

Our Geometry course develops reasoning, justification, and proof skills through an in-depth study of shapes and their properties, rigid transformations and congruence, and the relationship between similarity and right triangle trigonometry. Rich opportunities for problem solving culminate in the unit on surface area and volume. This course was created using the Common Core State Standards as a guide. The standards taught in each Math Medic Geometry lesson can be found here . Additionally, we've chosen to include a unit on Statistics and Probability that can be used as a stand-alone unit at any time during high school course work. The unit overviews and learning targets for the Math Medic Geometry course can be found here .

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Unit 4 Similarity and Right Triangle Trigonometry

Learning focus.

Describe the essential features of a dilation transformation.

Lesson Summary

In this lesson, we observed the key features of a dilation transformation while figuring out how a photocopy machine enlarges an image. We learned how to locate points on a dilated image by using the center and scale factor that define a specific dilation. We observed that “the same shape, different size” relationship between the pre-image and image figures are a consequence of the way dilations are defined.

Create similar figures by dilation given the scale factor.

Prove a theorem about the midlines of a triangle using dilations.

In this lesson, we extended our understanding of similar figures. Since corresponding segments of similar figures are proportional, and dilations produce similar figures, corresponding parts of an image and its pre-image after a dilation are proportional. We also learned that corresponding line segments in a dilation are parallel. These two observations provided a tool for proving a theorem about the midlines of a triangle, a segment connecting the midpoints of two sides of a triangle.

Determine criteria for triangle similarity.

In this lesson, we examined what it means to say that two figures are similar geometrically, and we examined conditions under which two triangles will be similar. We wrote and justified several theorems for triangle similarity criteria.

Prove that a line drawn parallel to one side of a triangle that intersects the other two sides divides the other two sides proportionally.

In a previous lesson, we learned that a midline of a triangle, a line that passes through the midpoints of two of the sides, is parallel to the third side and half its length. In this lesson, we extended this theorem to include other segments that cut the sides of a triangle proportionally. We also proved a non-intuitive “side-splitting” theorem about the multiple segments formed when multiple lines parallel to a side of a triangle cut the other two sides of the triangle.

Practice using geometric reasoning in computational work.

In this lesson, we drew upon a variety of theorems to support the computational work of finding missing sides and angles. To identify which theorems to use, we had to examine the available features of the diagram. For many measurements, multiple strategies could be used. We also used the diagram, along with our computed measurements, to develop and justify a conjecture for the sum of the interior angles of any polygon, similar to the theorem we proved previously about the sum of the interior angles in a triangle.

Locate the midpoint of a segment and a point that divides the segment in a given ratio.

In this lesson, we examined strategies for dividing a line segment into two parts that fit a given ratio. One common application of this concept is to find the coordinates of the midpoint of a segment, given the coordinates of the endpoints.

Prove the Pythagorean theorem algebraically.

In today’s lesson, we learned that drawing the altitude of a right triangle from the vertex at the right angle to the hypotenuse divides the right triangle into two smaller triangles that are similar to each other and to the original right triangle. We were able to prove the Pythagorean theorem using proportionality statements about the three similar triangles.

Investigate corresponding ratios of right triangles with the same acute angle.

In this lesson, we learned about some special ratios, called trigonometric ratios, that occur in right triangles. If two right triangles have a pair of corresponding acute angles that are congruent, the right triangles will be similar. Therefore, corresponding ratios of the sides of these two right triangles will be equal. This observation is so useful when working with right triangles that have the same acute angle that values of these ratios were recorded in tables for each acute angle between 0 ° and 90 ° .

Examine properties of trigonometric expressions.

In this lesson, we examined some relationships between trigonometric ratios, such as a relationship between the sine and cosine of complementary angles. We were able to use the properties of a right triangle, including the Pythagorean theorem that describes a relationship between the lengths of the sides, to justify the observations we made today.

Solve for the missing side and angle measures in a right triangle.

In this lesson, we extended our strategies for finding unknown sides and angles in a right triangle beyond using the Pythagorean theorem and the angle sum theorem for triangles, since sometimes we don’t have enough information in terms of side lengths or angle measures to use these theorems. We found that trigonometric ratios are useful in solving for unknown sides and that inverse trigonometric relationships are useful for finding unknown angles in a right triangle. Adding these tools allows us to find all of the missing sides and angles in a right triangle given two pieces of information: two sides of the triangle or one side and an angle.

Solve application problems using trigonometry.

In this lesson, we learned about the modeling process and how to use right triangle trigonometry to model many different types of applications, even applications that didn’t naturally include right triangles. A right triangle became a tool for representing a situation so we could draw upon trigonometric ratios and inverse trigonometric relationships to answer important problems in construction, aviation, transportation, and other contexts.