Question

How do you prove `sinx + cosx = -1`?

Answer 1

This can not be proven because it isn't true.

This is easy to see with a few test values of `x`

For example

`x=0 rarr sin(0)+cos(0) = 1 != -1`

`x=pi/4 rarr sin(pi/4)+cos(pi/4) = sqrt(2)`