geometry total review Flashcards
the intersection of 2 lines
point
intersection of 2 planes
line
collinear points are points that lie on the same
line
points and lines are coplanar if they lie on the same
plane
midpoint formula
x1 + x2/2 y1+ y2/2
distance formula
d= square root of (x2-x1) squared + (y2-y1) squared
circumference of a circle
(pi)(d)
area of a circle
(pi)(r)squared
perimeter of a square
4s
perimeter of a rectangle
2l+ 2w
area of a square
s(squared)
area of a rectangle
lw
area of a trapezoid
b1+b2/2 (h)
after a single line reflection OR an odd number of line reflections…
a figure will have a different orientation
after an even number of line reflections
a figure will have the same orientation
if reflected over the x axis, (x, y) becomes
(x, -y)
if reflected in the y-axis, (x,y) becomes
(-x,y)
if reflected in the line y=x, (x,y) becomes
(y,x)
if reflected in the line y=-x, (x,y) becomes
(-x,-y)
positive rotation
counterclockwise
negative rotation
clockwise
after rotation of 90, (x,y) becomes
(-x,y)
after rotation of 180, (x,y) becomes
(-x,-y)
after rotation of 270, (x,y) becomes
(x,-y)
if a figure has point symmetry…
the figure is its own image when rotated 180
when applying a composition of transformations
apply 2nd one first
glide reflection
reflection & transformation
invariant point
under transformation the point is the same
congruency transformation
pre image and image are congruent
similarity transformation
pre image and image are similar
*in a diagram, the face that the prism sits on is not always the base
the base must be congruent polygons
solids with a height and slant height
pyramid and cone
height vs slant height
height is perpendicular to the base, slant is height of the face
how is a cross section formed
when you slice through a solid object
number of faces of a solid determines max number of sides when you slice through a solid object
ex. cube has 6 faces, the largest polygon cross section that can be cut from a square pyramid is a hexagon, since a square pyramid has 5 faces, the largest cross section is a pentagon, since a triangular pyramid has 4 faces, the largest polygons cross section that cut from a triangular pyramid is a quadrilateral
possible cross sections of a cylinder
circle, oval, rectangle
all cross sections of a sphere
circles
rotating a cross section about an axis forms a solid
-rotating a rectangle around an axis forms a cylinder
- rotating a right triangle along an axis forms a cone
- rotating a semicircle along an axis forms a sphere
density formulas
density= mass/volume
population density= population/land area (water volume)
if a composition of transformation includes dilation, then that transformations
it’s a similarity transformation
a composition of line reflections over intersecting lines is equivalent to
a rotation
a composition of line reflectoins over 2 parallel lines/any odd number of parallel lines is equal to
single reflection
a composition of line reflections over 3 parallel lines is equal to
single reflection
to rotate/dilate a figure about a center other than the origin
1) translate the center of rotation to origin
2) apply that translation to each point in the figure
3) apply the rotation/dilation to those points, then translate back
a translation/dilation can prove
all circles are similar
given the graph of a figure and its image after a composition of transformations, first check to see if the pre image and image are equal so you can determine if the composition included a dilation, then check orientation of the pre image and image to determine if there was a reflection, then look for possible translations/rotations
parallel line have equal slopes
perpendicular lines have opposite negated slope
slope formula
y2-y1/x2-x1
slope intercept: y=mx + b
point slope: y-y1= m(x-x1)
horixontal line: y= #
vertical line: x= #
i think you find perpendicular bisector between 2 points by finding midpoint
find midpoint between the 2 points
corresponding angles are equal if 2 ll lines are cut by a transversal
if 2 lines cut by a transversal form supplementary same side exterior/interior angles
the lines are II
if 2 lines are perpendicular to the same line
the lines are ll
if a line is perpendicular to the same line
it is perpendicular to the other line
if 2 lines are II to the same line
the lines are II to each other
the construction of parallel lines can be justified using the theorem
If two lines and a transversal form alternate interior angles that are congruent, then the lines are parallel.
triangle angle sum theorem
<1 + <2 + <3 =180
exterior angle theorem
<1 + <2 + <4
point of congruency of angle bisectors of a triangle
incenter, always inside the circle
the point of concurrecy of the perpendicular bisectors of a triangle is
circumcenter
point of concurrency of the medians of a triangle is the
centroid
point of concureency of the altitudes of a triangle is
orthocenter
center of gravity/balance point of triangle
centroid
points of concurrency always inside a triangle
incenter, centroid
points of concruuency that could be inside, outside, or on the triangle
circumcenter, orthocenter
points of concruuency that could be inside, outside, or on the triangle
circumcenter, orthocenter
if the triangle is acute
circumcenter & orthocenter lie inside the triangle
if the triangle is obtuse
circumcenter and orthocenter is outside the triangle
if the triangle is right
the circumcenter lies midpoint of the hypotenuse and the orthocenter lies on the vertex that’s a right angle
centroid divides median of a triangle into 2 parts in
2/1 ratio