Geometry: Chapter 11
when using a proportion to find the area of one triangle when the other is given what proportion do you use?
(side 1/side2)2 cause area=area 1/ area 2
area of a square
1 times w
how many points determine a plane?
3
area of a triangle
BxH/2
why is it that if two lines intersect, then the lines are coplanar?
Once two lines intersect, you will have three noncollinear points, thus determining one plane
composite figure
a figure made out of simple shapes
one dimension
a line that has only one direction it has not width or depth
two dimension
a plane has both length and width but no depth
sector of a circle
a region of a circle bound by a central angle and its intercepted arc
what kind of a figure is a circle?
a two dimensional figure and not a polygon
area of a polygon
amount of flat space that fills in a polygon painting it
three dimension
an object, w/length, width, and depth or height
area of a parallelogram
base times height
what is the perimeter of a circle called
circumference
If two lines are perpendicular to the same plane then they are what?
coplanar
area of a rhombus
diagonal 1 times diagonal 2/2
three dimension
has depth surface area volume
area of a trapezoid
height (base 1+ BASE 2)/2
two dimensions
is flat polygons perimeter area
area of a rectangle
l times width
coplanar
lying in the same plane
Can we calculate pi using 3.14?
no because its not exact
if two planes are parallel then ___ of the lines contained in one plane will intersect any of the lines contained in the other plane.
none
Through a given point not on a plane, there passes how many lines perpendicular to the plane?
one and only one
through a given point there passes how many planes perpendicular to the given line containing the point?
one and only one
If a line intersects a plane, then it can intersect the plane at how many points?
only one
If two planes are perpendicular to the same line then then planes are what?
parallel
If a line is perpendicular to a plane then every plane containing the line is what to the given plane?
perpendicular
Two planes are perpendicular to each other if and only if one plane contains a line that is what to the second plane?
perpendicular
are of a circle
pi r 2
circumference of a circle
pi times diameter or 2 pi times radius
what formula do we use to find the area of the sector?
sec. for area/ entire area=central angle/ 360 or sector = central angle times pi r 2/360
if two figures are similar what do we know about the ratios of heir perimeters?
that its the same as the ratio of their sides
if two lines intersect then what are the lines?
the lines are then coplanar
perimeter of a polygon
the sum around the edges like putting up a fence
If a line is perpendicular to each of 2 intersecting lines at their point of intersection then what is the line to the plane determined by them?
then the line is perpendicular to the plane determined by them
what happens if you take 3 collinear points?
there can be more than one plane
through any 3 noncollinear points what happens?
there is exactly one plane
If a plane intersects two parallel planes then the intersection is what?
two parallel lines
parallel planes
two planes that will not intersect
If a line is perpendicular to a plane then any line perpendicular to the given line at its point of intersection with the given plan is it in the given plane?
yes
If you have a question like : a medium pizza has a diameter of 15 inches while a large has a diameter of 20 inches ho w much more pizza does the large have?
you find the areas and subtract
what about the ratio of their areas?
you square the length of that side to get the area and that's the ratio and you can simplify