Posted by Britt on .
{1/(sec x  1)}  {1/(sec x +1)} = 2 cot^2 x
solve using identities?

trigonometry 
Damon,
Hey, I did this for you long ago.

trigonometry 
Damon,
Twice in fact

trigonometry 
Damon,
copy again
sin a cos b + cos a sin b = sin (a+b)
so sin (7t)
1/(1/cos x 1)  1/(cos x +1)
cos x/(1  cos x)  cos x/(1+cos x)
[cos x(1+cos x)  cos x(1cos x)]/(1cos^2 x)
[ cos x + cos^2x  cos x +cos^2 x]/sin^2x
2 cos^2 x/sin^2 x
2 cot^2 x 
trigonometry 
Britt,
ohh, i didn't realize! thankyou :)

trigonometry 
Damon,
Please check before repeating posts. Some other teacher might have done it all over again.

trigonometry 
Britt,
okay!