# Sine & the graph of sin(x)

Note by rory.examtime, updated more than 1 year ago
 Created by rory.examtime over 7 years ago
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### Description

This note gives a definiton of sine of an angle, and explains the shape of the y = sin(x) graph

## Resource summary

### Page 1

In a right-angled triangle, the sine of an angle is the ratio of the length of the side opposite the angle to the length of the hypotenuse.

Sin(X) = O                 H

For example, in this triangle:

the sine of angle A (SinA) is 0.8, because the ratio of the opposite side (4) to the hypotenuse (5) is 4/5.

Graph of sin(x):

- Note that x is in radians, not degrees.

- This graph is often referred to as a wave, and has a period of 2π (after every 2π radians, the graph repeats it self)

- The graph has a max-value of y=1 and a min-value of y=-1. This is because the hypotenuse is always the longest side in a right-angled triangle.

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