Tuesday

October 21, 2014

October 21, 2014

Posted by **Christine** on Sunday, June 6, 2010 at 9:49pm.

cos(165) degrees

- Algebra 2 Honors -
**Reiny**, Sunday, June 6, 2010 at 9:54pmFor these type of questions, you must split up your given angles into a sum or a difference of angles whose trig ratios you know

e.g. 165 = 120+45

then cos(165)

= cos(120+45)

= cos120cos45 - sin120sin45

you should know both sin45 and cos45

for sin120,

sin120 = sin60

cos120 = -cos60

take it from here

**Answer this Question**

**Related Questions**

Trigonometry - use the appropriate trig identity (sum and difference, half angle...

TRIG/ALGEBRA - 1) Find the exact value. Use a sum or difference identity. tan (-...

Math- Trig - 1. Determine the exact value of cos^-1 (pi/2). Give number and ...

trig - use a sum or difference identity to find an exact value cos pie/12

Trig hep, please? Thank you! - 1. Find the exact value of sin(195(degrees)) 2. ...

trig - Find the exact value by using a half-angle identity. cos 22.5 degrees

math - Use the appropriate sum/difference formula to find the exact value of cos...

MATH - 1.)Find the exact solution algebriacally, if possible: (PLEASE SHOW ALL ...

Algebra II - Multiple Choice (theta) means the symbol 0 with the dash in it. 1.)...

Pre-Calculus-check answers - Use a sum or difference identity to find the exact ...