Why is the X-coordinate of the terminal side defined as cos θ?
Also why is the Y-coordinate of the terminal side defined as sin θ? Shouldn't sin θ = opposite side/hypotenuse which equals Y/hypotenuse? If so then why is sin θ taken to be Y only?
More Questions From This User See All
Answers & Comments
Verified answer
You are right,
sinθ = opposite/hypotenuse = Y/hypotenuse
So therefore,
Y = hypotenuse*sinθ
The thing is, for a unit circle, the radius (or hypotenuse) is 1, so this reduces to:
Y = 1 * sinθ
Y = sinθ
If you are not dealing with a unit circle, you need to multiply by the hypotenuse in order to find Y.