# sine & cosine of 30º and 60º

## Value of the sine and cosine of 30º and 60º

## Value of the sine and cosine of 30º and 60º

From an equilateral triangle, and with the help of Pythagoras, it is possible to determine the values of the sine and cosine of 30º and 60º.
Remember the definition of sine and cosine, for right triangles:
In an equilateral triangle, all three sides are equal, of 60º.
If the triangle is divided in half, from one vertex to the centre of the opposite side, the segment created is the bisection, that divides the angle in two, resulting a 30º angle, from a 60º angle.
From the right triangle that is formed, it is possible to determine the value of the side of unknown length, with the help of Pythagoras. Knowing the length of all sides, it is possible to know the values of the sine and cosine.
Versión en español:
https://www.geogebra.org/m/tyfzfep7

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