Question

determine the exact value of cos465°

Answer 1

\[a) \frac{ \sqrt{3}+\sqrt{2} }{ 2 }\]\[b) \frac{ \sqrt{2}+\sqrt{3}\sqrt{2}}{ 4 }\]\[c) \frac{ \sqrt{2}-\sqrt{3}\sqrt{2} }{ 4 }\]\[d) \frac{ 2+\sqrt{2}-\sqrt{3}\sqrt{2} }{ 4 }\]

Answer 2

\[\cos 465 = \cos 105 = \cos(60+45)\]
angle sum identity:
\[\cos(a+b) = \cos a \cos b - \sin a \sin b\]

Answer 3

hopefully that helps...you can get the values from a unit circle
only tricky part may be in simplifying the fraction

Answer 4

lol im trying to simplify it now xD

Answer 5

i got c ... is that right? :S @dumbcow

Answer 6

yep

Answer 7

really? YAY! thanks!

Answer 8

yw