Question

Reduce to one trig identity. sec(x)+sin(x)tan(-x)=? I know it equals cos(x) but how?

Answer 1

`secx+sinxtan(-x)=cosx`

Explanation:

We shall use the following identities:

`tan-=sin/cos`

`tan(-x)=-tanx`

`secx=1/cosx`

`"Prove that "secx+sinxtan(-x)=cosx`

`secx+sinxtan(-x)=1/cosx-sinxsinx/cosx=(1-sin^2x)/cosx=cos^2x/cosx=cosx " as required, "OEDelta`