Question

Use the appropriate identity to find the exact value of the expression: cos(15 degrees)

Answer 1

15 = 40 - 30 thus
\(\bf cos(15^o)\implies cos(45^o-30^o)\)

Answer 2

ahem 15 = 45-30 of course =) anyhow

Answer 3

So the final answer I got using the cos45cos30+sin45sin30 was \[[\sqrt6+\sqrt2]/4\]! Does that sound right?! Seriously thank you for all of your help, trig is not my strong suit.

Answer 4

yeap