Answer:
See proof below
Explanation:
In trigonometry identity
tan^2 theta = sin^2 theta /cos^2 theta
cot^2 theta = cos^2 theta/sin^2 theta
csc^2 theta = 1/sin^2 theta
Substitute into the expression
(sin^2 theta /cos^2 theta )+ (cos^2 theta/sin^2 theta)/1/sin^2 theta
= [sin^4theta + cos^4theta/cos^2 theta sin^2 theta]÷(1/sin^2 theta)
= 1/cos^2 theta sin^2 theta÷(1/sin^2 theta)
= 1/cos^2 theta sin^2 theta * sin^2 theta/1
= 1/cos^2theta
= sec^2theta (Proved!)