This week
Lessons 111, 112, 113, 114, & 115
Congruent and Similar Figures
Congruent Figures Similar Figures
• have the same size and • have the same shape shape but not the same size
Example: Example:
*Congruent lines or angles are marked using identical hash marks.
Mark congruent figures with hash marks. Label similar figures with an S.
Draw 2 congruent figures and 2 similar figures. Include hash marks. *Check student drawings
Transformations
Translation Reflection Rotation
• Slide • Flip • Turn
Symmetry: when a shape can be made to match up with itself in some way. Line of symmetry matches up exactly when folded or reflected in across the line
Figures with rotational symmetry match up exactly when spun or rotated.
Label the transformation.
Rotation Reflection Translation
EXAMPLE PROBLEM
Draw lines of symmetry for each figure.
Draw an example of each transformation. *Check student drawings.
Identify all lines of symmetry.
*infinite lines of symmetry
Classifying Triangles by Angles and by Sides
Acute Triangle Right Triangle Obtuse Triangle
• 3 acute angles • 1 right angle • 1 obtuse angle
The sum of the angle measures in a triangle is always 180°
Equilateral Isosceles Triangle Scalene Triangle Triangle • 3 congruent sides • 2 congruent sides • No congruent sides
Quadrilaterals
Quadrilateral Defining Feature Drawing Trapezoid Only 1 pair of parallel sides
Kite 2 pairs of adjacent congruent sides
Parallelogram • 2 pairs of parallel sides • congruent opposite sides
Rectangle Parallelograms with 4 right angles
Rhombus Parallelogram with all sides congruent Square Parallelogram with all sides congruent and 4 right angles
Draw an acute scalene triangle. Draw a right isosceles triangle.
Every square is also a quadrilateral, parallelogram, rectangle, kite and rhombus.
Possible or not? Explain why. - Scalene isosceles triangle No by definition.
- Right scalene triangle Possible
Name 3 parallelograms.
rectangle, rhombus, or square
A quadrilateral with exactly 1 pair of parallel sides is a trapezoid
explain the difference between congruent and similar figures. Suggested Answer: Congruent figures are exact copies, but similar figures can be different sizes.
| Work-text | Lesson 111 | Lesson 112 | Lesson 113 | Lesson 114 | Lesson 115 |
|---|---|---|---|---|---|
| Speed drill | 111 | 112 | 113 | 115 |
| Term | Meaning |
|---|---|
| congruent figures | Similar Figures |
| transformations | Translation Reflection Rotation |
| acute triangle | Right Triangle Obtuse Triangle |
| equilateral | Isosceles Triangle Scalene Triangle |
| quadrilaterals | Quadrilateral Defining Feature Drawing |
| trapezoid | Only 1 pair of parallel sides |
| rectangle | Parallelograms with 4 right angles |
| rhombus | Parallelogram with all sides |