Some practice problems for Test 2. Summer 2012
prove

1  sec x sin x tan x  sec2 x

cos  x  y   cos x cos y  sin x sin y

sec x  tan x 

sin 3 x  cos3 x
 tan x  1
cos x  sin x cos 2 x

1  cot 2 x  cos 2 x cot 2 x
sin x 
csc2 x
cos x
1  sin x
4
Solve

Find the exact value of
cos  a  b  if sin a  
7
8
, sin b 
, a is in quadrant IV, and b is in
25
17
quadrant II.

  using the identity tan 2  
Find the exact value of tan 75
x
1  cos x
. Your answer must be
1  cos x
simplified/rationalized completely.

Graph the function
f  x   6cos2 x  3
(This can be done without a calculator using identities and
what you learned from section 5.3)

If cos  
1
and  is in quadrant IV. Find the value of sin  2  .
5