Posted by John on Sunday, January 17, 2010 at 12:52pm.
Find the exact value of the trigonometric function:
sec(pi/12)
I am not sure how to answer this off the unit circle.

trig  Reiny, Sunday, January 17, 2010 at 2:05pm
You should know that
sec (pi/12)
= 1/cos(pi/12)
= 1/cos(pi/12)
You might find it "easier" to visualize degrees than radians, if so, the
pi/12 radians = 15º
so we need cos 15º
cos15 = cos(4530) ... (I am dropping the º symbol for easier typing)
= cos45cos30 + sin45sin30
= (√2/2)(√3/2) + (√2/2)(1/2)
= (√6 + √2)/4
and
cos(pi/12) = 4/(√6 + √2)
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