Using just the exponents...........of the two variables........and the one constant..................mathematicians would tell u that u cannot do that...........that that would be like adding apples and oranges....................but both are fruit.........seen from higher up...................more inclusive sets...................

But 1² is just 1, so:

x² + y² = 1
(the equation of the unit circle)

Also, since x=cos and y=sin, we get:

(cos(θ))² + (sin(θ))² = 1

a useful "identity"