Wednesday, December 14, 2011

December 14, 2011

Review of last week
Find a line that is perpendicular to another line
Remember: to find a perpendicular line the slope is the negative reciprocal
to find a parallel line the slope stays the same
always solve for b (the y intercept)


Writing Linear Equations

  • You must have the slope and the y=intercept in order to write a linear equation
  • to find the slope use the formula m = y2-y1/x2-x1
  • to find the y-intercept use the formula b = y - mx
Example:



Encourage teachers to think like their students as they discuss the attributes of the different shapes.  What are rules you would use to sort these shapes?
#41
1. No straight edges vs straight edges
2.  No vertices vs vertices
3.  Line segments vs line segments
4.  How many curves/curved sides
5.  Parallel lines
6.  Arcs
7.  Concave vs convex

1. Concave vs Convex
2.  Vertices
3.  # of Arcs
4. Angles vs no angles
1.  # of sides
2.  Angles
3.  Concave vs. convex
4.  Regular polygons vs irregular
5.  # of peaks
6. Parallel vs nonparallel
How would you sort these shapes?


How would you sort these shapes?


Relationship of the interior angles of a triangle - they add up to 180 degrees
The total sum of the exterior angles of a triangle are 360 degrees

Sorting triangles
E = equilateral triangle
H = equilateral triangle
J = Right triangle, isosceles
A = right, scalene
F = Right, scalene
I = right, scalene
B = isosceles
C = isosceles
L = scalene
G = isosceles
Types of triangles : 
  • scalene - all three sides are different lengths
  • isosceles - two sides of the triangle are the same length
  • equilateral - all three sides are equal in length
  • acute - all three angles are acute angles
  • obtuse - triangle has an obtuse angle
  • right - triangle has a right angle
**Technically in geometry you don't classify triangles as acute or obtuse**

Quadrilaterals


properties of sides:one pair of parallel sides, if non-parallel sides are equal the shape is an isosceles trapezoid
properties of angles = can be 2 acute or 2 obtuse

2 sets of parallel lines
4 sides
angels: opposite angles are the same
properties of diagonals - nothing special here
Properties of sides - all sides are parallel and equal in lengs
Properties of angles: all right angles
diagonals: perpendicular, bisect, and congruent

Properties of sides: opposite sides are parallel, opposite sides are equal in length
Properties of angles: all angles are right angles
diagonals: are not perpendicular, they always bisect each other, diagonals will alway create identical triangles
properties of sides: all sides are equal in length
properties of angles: opposite angles are equal, 2 obtuse and 2 acute
diagonals: perpendicular and bisect

Number of sides - 2 = how many triangles
number of triangle x 180 = sum of interior angles
The more sides of a polygon the smaller the exterior angles.  All exterior angles add up to 360 degrees.

Homework
Read: Beckman 599-602

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