Question

How do you prove `(sinx + tanx) / cosx + 1 = tanx`?

Answer 1

The given equation is not true and therefore can not be proven.

Explanation:

Consider for example the case when `x=0`

`color(white)("XXX")cos(0) = 1`
`color(white)("XXX")sin(0) = 0`

So when `x=0`
`color(white)("XXX")(sin x + tan x)/(cos x) + 1 = tan x +1`
which obviously can not be equal to
`color(white)("XXX")tan x`