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Chapter 7 and 10 concept map (Chapter 7: Symmetry and transformation…
Chapter 7 and 10 concept map
Chapter 7: Symmetry and transformation
Reflectional symmetry
The figure can be divided into two halves by one straight line
Both halves match each other completely if folded along the straight line
Straight line known as symmetry line
There can be more than one line of symmetry
Rotational Symmetry
If a figure repeats itself more than once when rotated about a fixed point, the figure is said to have rotational symmetry
If a figure repeats itself n times in one complete revolution
The figure is said to have n-fold rotational symmetry
Can also say order of rotational symmetry is n
n>1
Transformation
Translation
moving from one position to another
New figure known as image
new figure is retained
Reflection
reflected by a reflecting surface
Like a mirror
Have the same shape, size, but reversed orientation
Distance between figure and reflection line is same
Rotation
rotating a figure about a fixed point
through an angle in clockwise/anti-clockwise
Enlargement/Reduction
enlarging/reducing size
Shape and orientation is unchanged
Scale factor=every side x n(n=scale factor)
Reduction is same,but a decimal smaller than one
Chapter 10: coordinates
Rectangular coordinate system
A plane with a rectangular coordinate system is called a rectangular coordinate plane
Horizontal line is X-axis
Vertical line is called y-axis
Point of intersection of X- and Y- axis is O(origin)
The origin can also be represented as zero
When telling a coordinate of a point, tell X-axis first, then Y- axis
The two coordinate axis divide the rectangular coordinate plane into four regions
Also known as quadrant I,II,III,IV
Quadrant II=X-coordinate<0, Y-coordinate>0
Quadrant III=X-coordinate<0, Y-coordinate<0
Quadrant I=X-coordinate>0, Y-coordinate>0
Quadrant IV=X-coordinate>0, Y-coordinate<0
When anyone coordinate is 0, it is in no quadrant
Difference of line and line segment
Line has no end
Line segment has points
Polar coordinate
Alike of Rectangular coordinate plane
Instead of axis, uses circles
Circles surround pole (O)
Coordinates represented by degrees of a circle