Geometry Formulas and Definitions PDF

Units of measurements Length is a one-dimensional measure of part of an object, whereas distance is the space between objects. In the **Metric** system, the standard unit of length/distance is the **metre**. Other common units are the kilometre, centimetre and millimetre. Units of measurement: A...

Units of measurements Length is a one-dimensional measure of part of an object, whereas distance is the space between objects. In the **Metric** system, the standard unit of length/distance is the **metre**. Other common units are the kilometre, centimetre and millimetre. Units of measurement: A. Measuring Length millimetre (mm) centimetre (cm) metre (m) kilometre (km) b\. Measuring mass gram (g) kilogram (kg) tonne (t) c\. Measuring Volume/Capacity millilitre (ml) centilitre (cl) litre (l) **Perimeter** (*P*) is the distance around the outside of a two-dimensional, closed shape. All units must be the same when calculating perimeter. Sides with the same markings / dashes are equal in length. These markings are called **tick marks** or **hatch marks**. A **composite** (or **compound**) shape is made up of two or more basic shapes and can be decomposed into these shapes to support calculations. HOW TO CALCULATE THE PERMIETER: Look at your 2D shape and then list all the measurements you see, once you add them together you get your answer. A **circle** represents all the points the same distance from a centre point.\ The **radius** is the length from the centre to the edge. The **diameter** is the distance across the centre of the circle. The **circumference** is the circle perimeter. **Pi** (*𝜋*) provides a direct link between the diameter of a circle and its circumference.\ Pi is a non-repeating decimal that never ends! Common approximations include: - 3.14159 (to 5 decimal places) or 3.14 (to 2 decimal places) - *22 /7* (an approximate fraction) **Area** is described as the number of unit squares that fit inside a shape. If the size of the shape is known, the area can be calculated using **formulae.** \]If measurements are in: - Centimetres, then the area is being calculated in cm^2^ - Metres, then the area is being calculated in m^2^ Millimetres, then the area is being calculated in mm^2^ Basic shapes: rectangle, parallelogram and triangle Two **perpendicular** dimensions are used to find the area of these shapes. A rectangle= L x W for example, if the width of the rectangle was 2 cm and the length was 8 then you would times 2 by 8 to get the area of 16cm squared. A = **parallelogram** b x h for example if the base (width) of the parallelogram was 5cm and the height was 10 cm you would multiply 5 by 10 to get the area of 50cm square n geometry, three-dimensional shapes (3D shapes) are **solids** with three dimensions, such as length, width/depth and height. **Pyramids** have triangular sides that meet at a vertex. The shape on the base gives the pyramid its name. **Prisms** have rectangular sides and the shape.is the same all throughout. Drawing 3D shapes: - **Isometric** **paper** or grid paper supports accurate 3D drawings.\ - 2D representations of each view of the solid can be drawn, including the side, front and top views.\ A complete 2D representation can be drawn called a **net**: this is created by unfolding the solid and laying each face flat. **Volume** describes the size of a 3D shape: it is a measure of the 3-dimensional space, or the amount of space that a substance or object occupies. The volume of a **rectangular prism /** **cuboid** is given by the formula: for example first **𝑉= L X W X H** The volume of a **triangular prism** is half the volume of the cuboid. It is given by the formula: V- A x depth A is the area of the triangular base, and is found the triangular formula: A= BH/2