Why does cos(t)=x and sin(t)=y?

sin(-x) = -sin(x). sin(x) is an odd function. cos(-x) = -cos(x) cos(x) is an even function.

Derivative of sin(x) and cos(x), PROOF

Trigonometric Equation: Solve cos (x) - sin (x) = 0

Cos (Sin x) or Sin (Cos x), Which is Greater ?

sin(x)+cos(x)=sqrt(2) | Trigonometry

Proof that the Derivative of cos(x) is -sin(x) using the Limit Definition of the Derivative

dy/dx = cos x + sec²x and when x = 0 then y = 0, what is y?

Proof that the Derivative of sin(x) is cos(x) using the Limit Definition of the Derivative

Trigonometry Identities: sin(-x) = - sin(x) and cos(-x) = cos(x)

Sin(90-A), Sin(90+A), Cos(180-A), Cos(180+A), Sin(270-A), Sin(270+A),Cos(360-A) How Why Trigonometry

Trigonometric Equation: Solve sin (2x) = cos (x)

How to graph y=sin(x) and y=cos(x)

How to find cos(x) given that sin(x) = 3/5

Verify the Trigonometric Identity cos(pi/2 + x) = -sin(x)

Trigonometric Identity cosx + sin x = sq rt 2 cosx find cosx - sinx

Calculus Product Rule Example f(x) = sin(x)*cos(x)

Prove (sin x - sin y)/(cos x + cos y) = tan((x - y)/2)

Trigonometry Proof: cos (x + y) = cos x cos y – sin x sin y (https://youtu.be/b0o_dvFkYbU)

Prove cot x sin x = cos x