Posted by **Melinda** on Sunday, January 29, 2012 at 10:03pm.

Determine the exact value of cos 465 degrees

a) √3 + √2/2

b) √2 + √3√2/4

c)√2 - √3√2/4

d)2+√2-√3√2/4

- Precalculus -
**Reiny**, Sunday, January 29, 2012 at 10:10pm
cos 465°

= cos(105+360)°

= cos 105°

= cos(60+45)°

= cos60cos45 - sin60sin45

=(1/2)(√2/2) - (√3/2)(√2/2)

= (√2 - √6)/4

- Precalculus -
**Reiny**, Sunday, January 29, 2012 at 10:12pm
I think c) comes closest if you had typed it correctly as

(√2 - √3√2)/4 which then is the same as mine

- Precalculus -
**Melinda**, Sunday, January 29, 2012 at 10:20pm
Ok, thank you!

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