Thursday

April 24, 2014

April 24, 2014

Posted by **Lucy** on Saturday, August 30, 2008 at 10:10pm.

Answer: sqrt6-sqrt2/4

Thanks

- Pre-Calculus-check answers -
**Reiny**, Saturday, August 30, 2008 at 10:58pmYou might notice that 225 = 180 + 75

so sin 255 = sin(180+75)

= sin 180cos 75 + cos180sin75

= -sin75

now 75 = 45 + 30

so sin(75) = sin(45+30)

= sin45cos30 + cos45sin30

= (1/√2)(√3/2) + (1/√2)(1/2) or

= (√2/2)(√3/2) + )√2/2)(1/2)

= (√6 + √2)/4

so sin 255 = -(√6 + √2)/4

**Related Questions**

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

Algebra II - 1)Find the exact value of sin 165 degrees. Answer: (sqrt6 + sqrt2)/...

Algebra II - 1)Find the exact value of sin 165 degrees. Answer: (sqrt6 + sqrt2)/...

Algebra II - Find the exact value of cos 375 degrees. Answer: (sqrt6 + sqrt2)/4 ...

Calculus - I had this on a test: Use the half-angle formula to find the exact ...

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

Math - 1)Find the standard deviation of the data set to the nearest tenth. (21,...

Pre Calc. - Use the sum or difference identity to find the exact value of sin255...

Algebra - 1)A bookshelf holds 4 mysteries, 3 biograpghies, 1 book of poetry, and...

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