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GMAT > Geometry > Flashcards

Flashcards in Geometry Deck (63)
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1
Q

Can you assume lines to be straight?

A

Yes

2
Q

Can you assume lines to be perpendicular or parallel?

A

No

3
Q

When are shapes congruent?

A

When they are of the same size and shape. Orientation does not matter.

4
Q

If a line bisects a line and is perpendicular to it

A

Every point on the perpendicular bisector of a segment is equidistant from the two endpoints of the segment.

5
Q

Supplementary

A

180

6
Q

Compelmentary

A

90

7
Q

Sum of angles of a triangle

A

180

8
Q

Acute angles

A

At least two of the angles in a triangle have to be acute

9
Q

Largest angle always opposite

A

The longest side.

10
Q

The sum of two sides of a triangle

A

Greater than the third side

11
Q

The difference between the two sides of a triangle

A

Smaller than the third side

12
Q

The third side

A

Greater than the difference and less than the sum

13
Q

Can you assume that lines/angles that look similar or of the same length that they are?

A

No

14
Q

Assuming for problem solving

A

Figure is always drawn to scale so we can assume that two angles are similar or close to one another by just looking at them; we can also assume the angle measurements; just visual ESTIMATION

15
Q

Assuming for data sufficiency

A

Not always drawn to scale just use the information blatantly given to us

16
Q

For all the diagrams

A

Look big and look small (specially for triangles)

17
Q

Two way theorem-Isosceles triangle

A

Two angles opposite equal sides are equal

18
Q

Equilateral triangle

A

Three equal 60 angles and three equal sides

19
Q

Height

A

Segment from a vertex to the opposite side that is perpendicular*

20
Q

Base

A

Whatever side the height is hitting

21
Q

Right triangle area

A

Product of the two legs

22
Q

All three sides can be used as a base but

A

They all give you the same area

23
Q

Median

A

Line that goes from a vertex to the midpoint of the opposite side. Only divides that opposite side in half but does not divide the angle.

24
Q

Angle bisector

A

Divides the angle in half but not the opposite side.

25
Q

In an isosceles and equilateral triangle

A

The line from the non equal angle to the opposite side= divides the angle into two equal angles, is perpendicular to the base, divides the base into half, if one segment is playing more than one role= isosceles; divides into two congruent right triangle;

26
Q

Pythagorean triplet

A

3,4,5; 5,12,13; 8,15,17; 7,24,25; GCF times final answer

27
Q

Congruent Shapes

A

Same shape and same size= basically equal

28
Q

Similar shapes

A

Same shape but different sizes

29
Q

Similar triangles

A

All angles are equal, (or know that two angles are equal

30
Q

Similar triangles sides

A

Are proportional

31
Q

In similar triangles

A

Any lengths are smaller triangle times scale factos

32
Q

Similar triangles and the idea of scale factor

A

k

33
Q

Area of similar triangles

A

Scaled up by ksquared

34
Q

Halving and Doubling

A

Anything with 5 in the units digit double that and half the other one

35
Q

45-45-90 triangle

A

1:1: root two; we get this when we divide a a square into two along one or both of its diagonals

36
Q

30-60-90

A

1: root 3: 2

37
Q

Area of an equilateral triangle

A

root 3 over four s squared

38
Q

Sum of angles of a quadrilateral

A

360

39
Q

Every quadrilateral, diagonals

A

Exactly two

40
Q

Parellelogram

A

Opposite sides and angles are equal, sides are parellel, diagonals bisect each other; if any one of them is true all others are true

41
Q

Rhombus

A

Diamond, four equal sides, they are parallelogram, + all four sides are equal and diagonals are perpendicular (these diagonal properties can be true for other irregular quads)

42
Q

Rectangle

A

Special properties apart from the parallelogram: diagonals are congruent, not unique to rectangles

43
Q

Square

A

Parallelogram; rhombus, and a square

44
Q

Trapezoid

A

One set of parallel; if it is an isosceles trapezoid, then the non parallel sides are equal, opposite side angles are equal and diagonals are equal

45
Q

Length of a slanted line

A

Pytha

46
Q

Symmetrical trapezoid

A

Can divide into rectangle and two triangles on each side

47
Q

Area of a rhombus and a paralellogram

A

B*H where h is the altitude

48
Q

Area of a trapezoid

A

h * average of bases or divide it into two triangles and a rectangle**

49
Q

Diagonals pentagons

A

Five

50
Q

Hexagon diagonals

A

Nine

51
Q

Sum of angles for polygons

A

(n-2)* 180

52
Q

Regular polygon

A

Equal sides and equal angles; if a diagonal bisects the whole shape, it bisects the angle

53
Q

Pie

A

22/7

54
Q

Equal central angles

A

Equal arcs and equal chords

55
Q

Inscribed Angle

A

Vertex on the circle, inscribed angle is half the central angle and the arc

56
Q

If two different angles are drawn from the same chord

A

Then those two angles are equal; if they are on the same side of the chord

57
Q

If an angle is drawn from two end points of a diameter

A

90 degree angle

58
Q

Angle between radius and tangent point

A

90 degree

59
Q

Trick

A

Find the chord

60
Q

Space diagonal cuboid

one point to the opposite point of the other side

A

l squared + hsquared + b squared

61
Q

Space diagonal cube

A

square root of 3 a

62
Q

Cylinder volume and height

A

Volume= piersquaredh (base times height)

Surface area:2piersquared+ 2pierh

63
Q

Sphere

A

Every point is equidistant from the center; volume= 4/3 piersquaredcubed
Area: 4*pirsquared