Question

Question #d6a56

Answer 1

see below .

Explanation:

`Cos^2theta+tan^2theta-1=tan^2theta`
`1-sin^2theta+tan^2theta-1=tan^2theta` `color (green)((cos^2theta=1-sin^2theta))`

This gives
`cancel(1) - cancel(1)-sin^2theta+cancel (tan^2theta)=cancel(tan^2theta)`
So, `sin^2theta=0`
`color (blue)(sintheta=0)`

We could have got it in another way , see below :-
`Cos^2theta+cancel (tan^2theta)-1=cancel(tan^2theta)`
`cos^2theta=1`
`costheta=+-1`
Using identity mentioned in green , again we get
`color (blue)(sintheta=0)`
I'm leaving it here because there's no direction further .