Question

At what value sin and cos is negative aur positive.

Answer 1

zero is value sin and cos is negative nour positive.

Answer 2

HEY YOUR ANSWER IS .....

Changing the sign of θθ corresponds to going around in the other direction. Because θθ is measured from the positive xx-axis, all this does is to flip the endpoint over the xx-axis, as shown below.


Since cosine is the xx-component of PP, and sine is the yy component, flipping over the xx-axis will negate sinθsin⁡θ, but not cosθcos⁡θ. Hopefully this makes it clear why sine and cosine behave the way they do.

With tangent, just recall that tanθ=sinθcosθtan⁡θ=sin⁡θcos⁡θ, and since only one part of the fraction gets a −− sign, the tangent gets one as well.