Originally Posted by

**spoc21** Hi,

Im having a lot of trouble solving the following trig identities:

a) sec˛ x-2 sec x cos x + cos˛ = tan˛ x - sin˛ x

b) $\displaystyle tan x + 1/ tanx = 1/sin x cos x$

My working:

For a):

Trigonometric identity: secx cosx=1

Therefore:

sec˛x-2 sec x cos x + cos˛

=sec˛x + cos˛-2

Identity: sec˛x = 1/cos˛x

Use the Identity:

sec˛x + cos˛- 2

1/cos^2x +cos˛x-2

Now I am very confused, really unsure on how to prove this identity. I would greatly appreciate any helpful tips.

For b)

tanx+1/tanx =1/(sinx cosx )

L.H.S:

Tanx+1/tanx

Identity: 1/tanx = cotx :

=tanx+cotx

Now im completely lost, the R.H.S side is turning out to be "csc x sec x" .

I would greatly appreciate any helpful tips, since I'm very confused here.

Thanks :)