Answer:
theta = all real values
Explanation:
sec theta + tan theta = cos theta / (1-sin theta )
sec theta = 1/cos theta
tan theta = sin theta/cos theta
1/cos theta + sin theta /cos theta= cos theta/ (1-sin theta)
(1+ sin theta) / cos theta = cos theta /( 1-sin theta)
using cross products
(1+sin theta) * (1-sin theta) = cos theta * cos theta
1 +sin theta - sin theta- sin^2 theta= cos ^2 theta
1 - sin ^2 theta= cos ^2 theta
cos ^2 theta= cos ^2 theta
this is an identity so it is true for all theta