Question

Question #65e09

Answer 1

You can use trigonometric identities and simplify.

Explanation:

Here are two trigonometric identities that are needed in this problem:

`sin(a+b) = sin a cos b + cos a sin b`
`cos(a-b) = cos a cos b + sin a sin b`

We can rewrite the problem based on these identities.

`sin(y+π/2)+cos(y-π)=0`

`sin y cos (π/2) + cos y sin (π/2) + cos y cos (π) + sin y sin (π) = 0`

Using the unit circle, we can simplify.

`sin y * color(red)0 + cos y * color(red)1 + cos y * color(red)(-1) + sin y * color(red)0 = 0`

`cos y - cos y = 0`

`0 = 0`