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# Geometry

### Guide for First Test

Term | Definition |
---|---|

Ratio | A ratio is the comparison of 2 numbers or quantities |

Compression Ratio | Volume of cylinder with piston at the bottom of its stroke to vol. when the piston is at the top of the stroke. |

Aspect Ratio | Ratio of the length (or span) of an airfoil to its width (or chord) |

Glide Ratio | Ratio of forward distance traveled to vertical distance descended |

Air/Fuel Ratio | Ratio of weight of air to weight of fuel in the mixture being fed to the engine |

Gear/Speed Ratio | It is the ratio of the angular velocity of the input gear to the angular velocity of the output gear. |

Proportions | Statement of equality between 2 or more ratios |

Percentage | Parts out of one hundred, represented by % |

Algebra | Branch of mathematics that uses letters or symbols to represent variables in formulas and equations |

PEMDAS | Please Excuse My Dear Aunty Sally |

BODMAS | Brackets, Operations, Division, Multiplication, Addition, and Subtraction |

Geometry | Branch of mathematics that deals with shapes, sizes, relative position of figures, and the properties of space. |

Acute Angle | Angle less than 90 |

Right Angle | 90 degree angle |

Obtuse Angle | Greater than 90 degrees |

Straight Angle | line or 180 degree angle |

Reflex Angle | Angle that surrounds any angle |

Adjacent Angles | |

Vertical Angles | |

Linear Pair | |

Complementary Angles | When the sum of 2 angles = 90°, they are called complementary angles |

Supplementary Angles | When the sum of 2 angles = 180°, they are called supplementary angles |

Units for Angles | Degrees, radians |

Area | Measurement of the amount of surface of an object |

Sector | The plane figure enclosed by two radii of a circle and the arc between them. |

Polygon | A polygon is an enclosed shape made up of straight lines. |

Regular Polygon | A regular polygon has all its sides and angles equal. |

Apothem | The line joining the center of a regular polygon to the mid point of any of its sides |

Volume | The amount of space contained within a solid |

Cube | Cube is a special type of rectangular solid |

Cylinder | Solid having the shape of a can, or length of a pipe, or a barrel |

Piston Displacement | Total volume (in cubic inches, cubic centimeters, or liters) swept by all of the pistons of a reciprocating engine as they move in one revolution of the crankshaft |

Sphere | Solid having the shape of a ball (constant D) |

Cone | Solid with base as a circle, and sides tapered to a point |

Surface Area of 3-D Solids | Sum of all the areas of the faces of a solid |

Polyhedrons | -They have flat polygonal faces, straight edges, and sharp corners on vertices -They are based on polygons -They have no curved faces |

Prisms | Prisms are simple polyhedrons that have identical polygon ends and flat parallelograms sides |

Pyramids | Pyramids are polyhedrons with a polygon base and sides meeting at a top point or apex |

Trigonometry | The branch of mathematics that studies relationships involving lengths and angles of triangles. |

Right Triangle | A triangles that has 90 degrees |

Oblique Triangle | A triangle that is not a right triangle. There are two kinds of oblique triangles: Acute (all its angles are less than 90, and Obtuse triangles (has one obtuse angle). |

Equilateral Triangle | All its sides and angles are equal |

Isosceles Triangle | Two sides are equal. Angles opposite to equal sides are equal |

Scalene Triangle | The three angles and sides are unequal |

Angle of elevation | Angle produced by an object which is higher than the fixed view... |

Angle of depression | Angle produces by an object which is lower to the perspective view. |