ch 11, like all of it Flashcards
Area of a parallelogram
A=bh
Area of a triangle
A=1/2(bh)
Area of a rhombus
A= [ d1(d2) ] 1/2
OR
A= bh (depends on the info you have)
Area of a trapezoid
A = 1/2h (b1 + b2)
The radius of a polygon inscribed in a circle goes from the center to the…
…vertex of the polygon
The radius of a polygon inscribed inside a circle is from the center of the polygon/circle to the…
…vertex of the polygon
A central angle is formed by-
-two radii drawn to the consecutive vertices
Apothem
the perpendicular distance from the center of the polygon to a side
Formula to find the area of a regular polygon
A= 1/2 a (apothem) times p (perimeter)
The area of a regular polygon is equal to half-
-the product of the apothem and the perimeter
Circumference
C=2π r
Area of a circle
A=π r^2
EX:
A ferris wheel has a diameter of 42 ft. How far will a rider travel during a 4-min ride if the wheel rotates once every 20 seconds?
there are 12 20 seconds in 4 minutes,
c= 2π * 21 = 42π * 12
505π ft
Arc length formula
m of arc/360 times 2π r
Area of sector
m of arc/360 times π r^2
If two triangles have 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
If the scale factor of two similar figures is a : b, then (2)
1) The ratio of the perimeters is a : b
2) The ratio of the areas is a^2 : b^2
Imagine circle R is in circle S*
Suppose a point P of region S is picked at random. The probability that P is in region R equals-
R= Area of R/ Area of S
