Geometry: Chalter 11 Flashcards
Postulate 18
Area congruence postulate
If two figures are congruent then they have the same area
Postulate 17
The area of a square is the square of the length of a side.
A=s^2
Postulate 19
Area addition postulate
The area of the region is the sum of the areas of it’s nonoverlapping parts
Theorem 11-1
The area of a rectangle equals the product of its base and height
A=bh
Theorem 11-2
The area of a parallelogram equals the product of a base and the hate to that base
A=bh
Theorem 11-3
The area of a triangle equals half the product of a base and the height to that base
A=bh
Theorem 11-4
The area of a rhombus equals half the product of it’s diagonals
A=1/2d(1)d(2)
Theorem 11-5
The area of a trapezoid equals half the product of the height and the sum of the bases
A=1/2h(b{1}+b{2})
Center of a regular polygon
The center of the circumscribed circle
Radius of a regular polygon
Distance from the center to a vertex
Central angle of the regular polygon
Angle formed by two radii drawn to consecutive vertices
Apothem of a regular polygon
Perpendicular distance from the center of the polygon to a side
Theorem 11-6
The area of a regular polygon is equal to half the product of the apothem and the perimeter
A=1/2ap
Formula for the length of a sector
X/360*2pi.r
Formula for area of a sector
X/360*pi.r^2
If two triangles of equal heights then
The ratio of their areas equals the ratio of their bases
If two triangles have equal bases then
The ratio of their areas equals the ratio of their heights
If two triangles are similar then
The ratio of their areas equals the square of their scale factor
Theorem 11-7
If the scale factor of two similar figures is a:b then
The ratio of the perimeter is a:b
The ratio of the area is a^2:b^2
