# pythagoras and trigonometry notes

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- Created by: louisepardoe
- Created on: 22-05-16 14:22

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**pythagoras' theorem**

a squared + b squared = c squared (C grade)

- only works for right angled triangles
- uses 2 sides to find the 3rd side
- make sure you get the numbers in the right place
- c is the longest side (called the hypotenuse) and it's always opposite the right angle
- check that your answer is sensible

use pythagoras to find the distance between two points (c grade)

- draw a sketch to show the right-angled triangle
- find the lengths of the shorter sides of the triangle
- use pythagoras to find the length of the hypotenuse

**trigonometry- Sin, Cos, Tan**

the 3 trigonometry formulas (b grade)

- three basic trig formulas
- each one links two sides and an angle of a right-angled triangle
- sin x = opposite divided by hypotenuse
- cos x = adjacent divided by hypotenuse
- tan x = oppositve divided by adjacent
- hypotenuse is the longest side
- opposite is the side opposite the angle being used
- adjacent is the side next to the angle being used
- work out which two sides of the triangle are involved in the question
- pick the formula that involves those sides
- to find the angle- use the inverse followed by sin, cos or tan
- make sure your calculator is in deg mode
- your calculator will display sin, cos or tan to the power of -1
- only works for right angled triangles

angles of elevation and depression (b grade)

- angle of depression is angle downwards from the horizontal
- angle of elevation is angle upwards from the horizontal
- …

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