Answer:
The unit circle centered at the origin in the Euclidean plane is defined by the equation:
[tex]x^2+y^2=1\\[/tex]
Given an angle , there is a unique point P on the unit circle at an angle θ from the x-axis, and the x- and y-coordinates of P are:
[tex]x=cos \theta \\y = sin \theta[/tex]
Consequently, from the equation for the unit circle:
[tex]cos^2\theta+sin^2\theta=1[/tex]
the Pythagorean identity.
