Wednesday

August 20, 2014

August 20, 2014

Posted by **jj reddick** on Monday, October 25, 2010 at 4:15am.

- trig -
**jai**, Monday, October 25, 2010 at 8:34amnote that 13pi/12 is also 195 degrees, which can be expressed as difference of two angles, 240 - 45:

sin(13pi/12) = sin(195) = sin(240-45)

*expanding this,

sin(240)cos(45)-cos(240)sin(45)

(-sqrt(3)/2)(sqrt(2)/2)-(-1/2)(sqrt(2)/2)

(-sqrt(6)/4)+(sqrt(2)/4)

therefore:

{[sqrt(2)-sqrt(6)]/4}

so there,, :)

**Related Questions**

Precalculus/Trig 6 - Find the exact value of the following trigonometric ...

trig - find exact value cos(13pi/15)cos(-pi/5)-sin(13pi/15)sin(-pi/5)

Math - Given that cos 13pi/18=sin y, first express 13pi/18 as a sum of pi/2 and ...

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

Trigonometry - If cos(a)=1/2 and sin(b)=2/3, find sin(a+b), if 1) Both angles ...

pre-calculus - use a sum or difference formula to find the exact of the ...

trig - simplifying trigonometric expression a) sinx/tanx cosx b)sin^4a + sin^2a ...

Alg2/Trig - Find the exact value of the trigonometric function given that sin u...

math - Eliminate the parameter (What does that mean?) and write a rectangular ...

trig - Find the exact value of the trigonometric function given that sin u = &#...