## Glossary of GRE General Test Math Flashcards

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- What are the first 10 prime numbers?
- 2, 3, 5, 7, 11, 13, 17, 19, 23, 29

- Adding Fractions:

5/6 + 2/3 - -Find the LCM:

5/6 + 2/3 LCM of 6 and 3 is 6

5/6 * 1/1 + 2/3 * 2/2 equals:

5/6 + 4/6 = 9/6 or 3/2

- Subtracting Fractions:

3/4 - 2/3 - -Find the LCM:

3/4 - 2/3 LCM of 4 & 3 is 12

3/4 * 3/3 - 2/3 * 4/4 equals:

9/12 - 8/12 = 1/12

- Dividing Fractions:

2/5 / 7/8 - -flip the fraction you're dividing by, then multiply:

2/5 / 7/8 = 2/5 * 8/7= 16/35

- Multiplying Fractions:

-10/4 * 3/5 - Simply Multiply:

-10/4 * 3/5 = -30/20 = -3/2

- How do you convert a mixed fraction into a pure fraction?

Ex: 3 2/7 - * integer by denominator & add product to numerator:

3 2/7 = 23/7

- How do you convert a fraction to a decimal?

Ex: 2/7 - Divide the top by the bottom:

2/7 = 7 divided by 2 = .28

- When can you add and subtract exponents?
- When they share the same base and the same power:

3x to the 2nd & 2x to the 2nd = 5x to the 2

- When can you multiply and divide exponents and roots?
- When they share a base:

x to the 2nd * x to the 3rd = x to the 5th

x to the 2nd / x to the 3rd = x to the 1st

- How do you raise the power of an exponent?

Ex: (x to the a)to the b

Ex: (x to the 2nd)to the 3rd - (x to the a) to the b =

x to the ab

(x to the 2nd) to the 3rd =

x to the 6th

- What is the definition of a cube root?
- a # divided by itself twice

EX: the cube root of 27 is 3 because 27 / 3 = 9 and 9 / 3 = 3

- What is the square root of 9?
- The square root of 9 is 3

- Acute Angle
- An angle with less than 90 degrees

- Right Angle
- An angle measuring 90 degres

- Obtuse Angle
- An angle measuring more than 90 and less than 180 degrees

- Complementary Angles
- Angles whose sums measure 90 degrees

- Supplementary Angles
- Angles whose sums measure 180 degrees

- Adjacent Angles
- Angles who share a common side and a common vertex

- Vertical Angles
- Angles opposite each other when 2 straight lines intersect, forming 4 angles. They are always equal.

- Perpendicular Lines
- 2 lines that meet to for right ngles.

- Parallel Lines
- Two or more lines that remain the same distance apart at all times.

- Corresponding Angles
- Identical angles

- Polygon
- Closed shape/figure in a plane with three or more sides

- Regular Polygon
- All sides have the same length and all angles have the same measure

- Convex Polygon
- All diagonals are within the figure

- Concave Polygon
- At least one diagonal is outside the figure

- Diagonals of Polygons
- Line segment connecting one vertex with another vertex. It isn't a side.

- Scalene Triangle
- A triangle with no equal sides

- Right Triangle
- A triangle with a right angle in its interior

- Every triangle has 3 ____ and 3 _______
- bases (bottom sides) and heights (altitudes), heights being the perpendicular distance from a vertext it its opposite side

- Triangle Median
- The line segment drawn from a vertext to the midpoint of the opposite side

- Rule for angles that are opposite from equl sides
- They are also equal

- Rule for the location of large and small angles in any triangle
- The longest side is always opposite from the largest angle. Same for the shortest.

- Rule for the sum of the lengths of the sides of a triangle
- The sum of the lengths of any 2 sides must be larger than the lengh of the 3rd side.

- Exterior Angle
- If 1 side of a triangle is extended, the exterior angle formed = the sum of the other 2 interior angles

- Hypotenuse
- The side opposite the right angle in a right triangle

- Pythagorean Theorem for right triangles
- the 3 lengths, a, b, and c will always be #'s such that:

a^2 + b^2 = c^2

- Isoceles Right Triangle
- Has characteristics of both isoceles/right triangles: 2 equal sides, 2 equal angles, and one right angle

- Rule for ratio of the sides of an isoceles right triangle
- The sides are always:

__

x, x, and X/2

- Ratio of the sides of a 30, 60, 90 triangle
- __

X, 2x, x/3

-Side opposite 30 is x, side opposite 60 is x/3, side opposite 90 is 2x

- Quadrilateral
- Polygon w/4 sides

Sum of angles: 360 degrees

- Parallelogram
- Opp. sides are equal/parallel

Angles equal

Consec. angles supplementary

Diagonals not always equal

- Rhombus
- -Parallelogram with 4 equal sides

-Diagonals not always equal

- Trapezoid
- -1 pair of parallel sides

- Formula for Interior Angles of a polygon
- (n-2)180, n = the # of sides

- Formula for the perimeter of a polygon
- The sum of the sides

- Formula for the area of a triangle
- A= 1/2bh

- Formula for the area of a square/rectangle
- A= lw

- Formula for the area of a parallelogram
- A= bh

- Formula for the area of a trapezoid
- A= 1/2(b1 + b2)h

- Diameter
- A straight line segment passing through the center of the circle. It is 2 times the length of the radius

- Chord
- Line segment whose endpoints lie on the circle

- Arc
- distance between any 2 points on the rim of the circle

- Formula for circumference of a circle
- C = 2(pi)(r), pi = 3.14

- Formula for area of a circle
- A = (pi)r^2

- Central Angle
- Angle formed by any 2 radii in a circle

c.a. = measure of intercepted arc

- Inscribed Angle
- the angle formed by any 2 chords that meet on the circle

i.a. = 1/2 measure of intercepted arc

- Formula for Calculating Interest
- principal * rate * time = Interest

- How do you change a fraction to a percent?

Ex: 2/5 - 1. change to a decimal

2. Change the decimal to a percent

Ex: 2/5 = .4 = 40%

- How do you change a percent to a fraction?

Ex: 60% - 1. Drop the %

2. Write over 100

3. Reduce if necessary

Ex: 60% = 60/100 = 3/5

- How do you determine the percent of a number?

Ex: 20% of 80 - Change % to a fraction or decimal and multiply

20/100 * 80 = 1600/100 or 16

- 18 is what percent of 90?
- 18 = x(90)

18/90 = x

1/5 = x

20% = x

- 10 is 50% of what number?
- 10 = .50(x)

10/.50 = x

20 = x

- Formula for finding Percent Increase/Decrease

Ex: % decrease of a $500 item on sale for $400? - change/starting point = % change

100/500 = 1/5 = 20%

- Inscribed angles
- angles formed by 2 chords of a circle that meet on the circle

They equal 1/2 measure of intercepted arc

- Concentric Circles
- Circles with the same center

- Tangent

2 Tangents drawn from the same point on a circle are... - A line touching a circle at only 1 point

= in length and perpendic. to a radius meeting at that point

- Congruent geometric figures
- Identical in size and shape

- Similar geometric shapes
- Have the same shape but aren't identical in size

- Volume of a solid figure
- The # of cubic units of space the figure contains. AKA "cubic units".

- Formula for finding the area of a solid figure
- A = b * h

- Formula for the volume of a cube
- V = s * s * s = s^3

- Formula for the volume of a rectangular solid
- V = (lw)(h) = lwh

- Formula for the volume of a right circular cylinder (circular bases)
- V = (PIr^2)h = PIr^2h

- Raising a fraction b/t 0 and 1 results in a...

(1/2)^2 = - Number smaller than 1:

(1/2)^2 = 1/4

- Factor

Factors of 12: - A number that can be divided by another number without leaving a remainder:

2,3,3,4,6, 12

- Shortcut for comparing

3/7 and 7/14 - Multiply diagonally up from each denominator:

14 * 3 and 7 * 7

- Permutation
- Arrangement of things in a definite order:

4 factorial: 4 * 3 * 2 * 1

- Probability
- Equal to the outcome you're looking for divided by the total outcomes

- Reciprocal

Reciprocal of 1/2 - The inverse of something:

2/1