Question #d6a56

1 Answer
Jan 7, 2018

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 .