Question

The x in the problem is actually theta...so...
show that 1+cot^2x - cos^2x-cos^2xcot2x=1

Answer 1

so for the first step you need to know that

cot x = (cos x)/(sin x)

so than now you need just rewriting your equation using this and after make the calcules with common denominator and will see how you can getting on the right part 1

hope so much that this is usefull for solve your exercise