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area of triangle
1/2 base x height
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pythagorean theorem
only for right triangles
a2 + b2 = c2
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right triangle ratios
(4)
- 3:4:5
- 5:12:13
- s : s : s/2
- s : s/3 : 2s
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area of rhombus, 4 equal sides, 4 angles that aren't necessary right angles
1/2 d1 d2
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area of parallelogram
2 opposite and equal pairs of sides
base x height
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area of rapezoid
1/2 (b1 + b2) x h
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total interior angle
(n-2) 180
n=number of sides
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average measure of one angle in polygon
(n-2)180 / n
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volume of polygon
area of the base x height
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volume of a cylinder
(pie r2) height
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total surface area of a cube
6e2
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total surface area of rectangular solid
2(l w) + 2 (w h) + 2 (h l)
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total surface area of a cylinder
(circumference x height) + 2(pie r2)
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distance between 2 points
/ (x2 - x1)2 + (y2 - y1)2
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circumference of circle
2pie r
pie d
-
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length of an arc
- 1. find the circumference of the circle (2pie r, pie d)
- 2. put the degree measure* of the arc over 360, reduce fraction
- 3. multiply circumference by the fraction
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area of a sector
- 1. find area of the circle (r2)
- 2 . put degree measure* of sector over 360, reduce
- 3. multiply the area by the fraction
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equations for FOIL
- (a+b)2 = a2 + 2ab + b2 (a-b)2 = a2 - 2ab + b2 (a-b)(a+b) = a2 - b2
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find probability
number of possible desired outcomes/ number of total possible outcomes
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find distance
- distance = rate x time
- time = distance/ rate
- etc
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average
sum/ number of terms
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average common sense way
average is 90
numbers: 89, 88, 93, 92 90
-1, -2, +3, +2
- = +2
- need to get 88 to get average (subtract the number extra or add number needed)
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percent increase or decrease
number increase or decrease/ original whole
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interest problems
- PRTI
- Principal x Rate x Time = Interest
- principal:amount money begin with
- rate: interest rate you're earning on the money, expressed as a decimal
- time: amt of time (years) money left in account
- interest: amt of interest earn on the investment
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work
time put in/ capacity, time to do the whole job
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