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ACT formulas 2
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ACT formulas 2
different formulas used on the ACT off of EriktheRed tutoring
Question  Answer 

volume for a right cylinder  pi x r^2 x h 
area of a trapezoid  (base_1 + base_2/2) x h base 1 is on the bottom, base 2 is on the top, the height is the dotted line with the right angle 
Area for a rhombus if l=w  lh 
formula for the length of an arc  (n^0/360^0) x 2 x pi x r 
formula for the area of a sector of a circle  (n^0/360^0) x pi x r^2 
definition of similar triangles  they have the same shape. The corresponding angles are equal, and the corresponding sides are in proportion. For example, the 3–4–5 triangle and the 6–8–10 triangle 
the length of on side of a triangle is ALWAYS  less that the sum and more than the difference of the lengths of the other two sides 
for a special right triangle with 1 90 degree angle and 2 45 degree angles  the hyp is x√2 and the legs are both x 
parallel lines  have equal slopes 
perpendicular lines  have negative reciprocal slopes : m_1 x m_2=1 
cosecant (csc)  opposite of cosine; c/b or hypotenuse/adjacent 
cotangent (cot)  opposite of tangent; b/a or adjacent/opposite 
secant (sec)  opposite of sine; c/a or hypotenuse/opposie 
how do you average evenly spaced numbers  average the smallest and the largest. the average of all the integers between 13 and 77 is the same as the average of 13 and 77 
how many degrees are on the outside of of a triangle?  360 
rectangle  a four sided figure with four right angles 
parallelogram  has two pairs of parallel sides 
square  a rectangle with 4 equal sides 
trapezoid  a quadrilateral with one pair of parallel sides and one pair of non parallel sides 
how do you find the percent of increase or decrease?  add or subtract the percent number to 100 percent and multiply it by the original number 
to find the original whole before a percent  set up an equation: think of 15%increase over x as 1.15x; 
how do you find the combined percent increase and decrease?  take the percents off or on to 100% 
how to find parttopart and wholetowhole ratios  put each number in the original ratio over the sum of numbers 
average rate  you combine the total distance and divide it by the total time 
how do you find the sum from the average  sum= average x number of terms 
how do you find equations that are in terms of the other variables  it means to isolate the one variable on one side of the equation 
how to solve for absolute values  take the equation and make two: one side equals to the positive answer and the other equals to a negative answer 
when do you use a solid circle or an empty circle in graphing inequalities  you use a solid circle if the point is included and an empty circle if the point is not included 
equation for a circle in a graph with r as radius and centered at (h,k)  (xh)^2 + (yk)^2=r^2 
the form of an equation that makes a parabola  y= ax^2 + bx + c 
in a 51213 triangle  the sides are all in 51213 ratios: if one side is 39 and another side is 36, then the final leg is 15 
the sum of the measures of the interior angles of a polygon is  (n2)x180; n=number of sides 
how to find one angle of a regular polygon  divide the sum of the angles by the number of angles(which is the same as the number of sides 
to find the interior angle of a polygon  ((n2)x180)/n 
formula for the surface area of a rectangular solid  2lw + 2wh + 2lh 
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