If you place this angle on a graph, it will be in the third quadrant, 45° below the x-axis.
The sides of a 45° - 45° - 90° triangle are 1 - 1 - √(2)
Labeling the three sides: the hypotenuse is '1', the horizontal (x-value) is '-1', and the vertical (y-value) is also '-1'.
The value of sin is the y-value divided by the hypotenuse: sin(225°) = - 1 / √(2).
Rationalizing the denominator, sin(225°) = - √(2 / 2).
If you place this angle on a graph, it will be in the third quadrant, 45° below the x-axis.
The sides of a 45° - 45° - 90° triangle are 1 - 1 - √(2)
Labeling the three sides: the hypotenuse is '1', the horizontal (x-value) is '-1', and the vertical (y-value) is also '-1'.
The value of sin is the y-value divided by the hypotenuse: sin(225°) = - 1 / √(2).
Rationalizing the denominator, sin(225°) = - √(2 / 2).