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36 Cards in this Set
- Front
- Back
Geometry Problem solving
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You can trust what you see. Figures are drawn to scare unless a problem states otherwise.
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Geometry Data Sufficiency
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Be wary of what you see. Figures are not necessarily drawn to scale, and they may be drawn inaccurately in order to confuse you.
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Geometry Transcription
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Make sure you have correctly transcribed the diagram before you begin solving a problem. If no diagram is provided, draw one yourself.
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Lines & Angles
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Two points determine a line.
Angle are measured in degrees, and a complete circle contains 360°. A straight line contains 180°. |
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Intersecting Lines
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When two straight lines intersect, the angles opposite each other are equal. These are called vertical angles or opposite angles.
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Perpendicular Lines
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An angle of 90° is a right angle. two lines that meet at a right angle are perpendicular, indicated by the ⊥ symbol.
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Parallel Lines
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If two lines in a plane never intersect, they are parallel, denoted by the symbol ∥.
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Line crossing parallel line
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Two kind of angle are formed: big angles and small angles.
All big angles are equal, and all small angles are equal. Any big angle plus any small angle equals 180°. |
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Parallelograms
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Four-sided figures made up of two pairs of parallel lines.
The opposite big angles are equal, the opposite small angles are equal. and the sum of any big angle and small angle is 180°. |
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Triangles
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A three-sided figure with three corresponding angles.
The points where the sides meet are called vertices (each corner is called a vertex). Perimeter is sum of lengths of its sides. |
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Triangles & Angle relationships
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In any triangle, larger sides are opposite larger angles.
Smaller sides are opposite smaller angles. Equal sides are opposite equal angles. |
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Area of Triangle
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A= 1/2bh
Any side of triangle can serve as the base. Key is to remember that the height must be perpendicular to the base. |
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Equilateral triangles
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Have three equal sides and three equal angles @ 60°.
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Isosceles Triangles
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Have two equal sides, and the two angles opposite those sides are also equal.
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Right triangles
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Contain one right 90° angle. The side opposite the right angle is called the hypotenuse and it is the longest side of the triangle. The other two sides are called the legs.
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Impossible triangles
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The length of any side of a triangle must be less than the sum of the other two sides and greater than the difference between the other two sides.
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Quadrilaterals
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A four-sided figure. Has 360°.
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Parallelograms
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Opposite sides are equal and parallel.
Opposite angles are equal. Adjacent angles add up to 180° (big angle + small angle = 180°) Area = bh (height must be perpendicular to the base) |
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Rectangles
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Parallelogram with four right angles.
Area = lw Perimeter = 2(l + w) or 2l + 2w |
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Squares
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Area = s^2
Perimeter = 4s |
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Circles - Radius
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The distance from the center of the circle out to the edge. All radii are equal.
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Circles - Chord
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A line segment from one point on the circle to another.
A chord that passes through the center of the circle is called a diameter. The diameter is the longest chord in the circle. d = 2r |
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Circle - Circumference
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The distance around a circle.
Circumference = πd or 2πr |
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Circle - Arc
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A piece of a circle (a portion of the circumference)
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Circle - π
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Relationship between the circumference of any circle and its diameter.
Circumference is π times the diameter. |
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Circle - Area
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Area = πr^2
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Circle - Central Angle
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If x is measure of central angle, the length of arc is x/360 times the circumference of entire circle and the area of a sector is x/360 times the area of the entire circle.
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Coordinate Geometry
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Horizontal x-axis; Vertical y-axis
Origin is the intersection of the axes and has the coordinates (0,0). A line that rises from left to right has a positive slope. A line that falls from left to right has a negative slope. A horizontal line has a slope of 0. |
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Solid Geometry
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Rectangular solid v = lwh
Cube v = s^3 Cylinder v = πr^2h Surface area is the combined area of all the surfaces of a solid. |
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Types of right triangles
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3-4-5
6-8-10 5-12-13 |
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45:45:90
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x,x, x√2
2, 2, 2√2 |
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30:60:90
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x,x√3, 2x
5, 5√3,10 |
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y = mx + b
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x and y are coordinates
m is the slope b is the point (0,b) where the line crosses the y-axis |
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Area of Equilateral Triangle
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s^2√3
--------- 4 |
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Diagonal formula
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a^2 + b^2 + c^2 = d^2
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Surface area of a box
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2 lw + 2 lh + 2 hw
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