Monday

December 22, 2014

December 22, 2014

Posted by **Amandeep** on Thursday, May 1, 2008 at 12:12am.

Find sin2x and cos2x

How to get the answers of sin2x = 120/169 and cos 2x = 119/169?

- trig -
**Reiny**, Thursday, May 1, 2008 at 8:28amtanx = 5/12

r^2 = x^2 + y^2

= 12^2 + 5^2

r = 13

tanx >0 and sinx<0, so x must be in quad. III and

and sinx = -5/13 , cosx = -12/13

sin 2x = 2sinxcosx = 2(-5/13)(-12/13)

= 120/169

cos 2x = cos^2 x - sin^2 x

= 144/169-25/169

=119/169

do the others the same way, or the way

drwls showed you in the other post.

**Answer this Question**

**Related Questions**

trig - sinx = 4/5 and x terminates in Quadrant II Find sin2x and cos2x How to ...

Math please help quick - Which of the following are identities? Check all that ...

Trig - Prove the following functions: (sinx+sin2x)/(1+cosx+cos2x)=tan x (cos3x/...

maths - prove that 1+sin2x-cos2x / sin2x+cos2x = tanx

Trig - Verify the identity: tanx(cos2x) = sin2x - tanx Left Side = (sinx/cosx)(...

trig - write sin4xcos2 as the sum or difference of two functions. answers: 1/2(...

trig - write sin4xcos2 as the sum or difference of two functions. answers: 1/2(...

trig - write sin4xcos2 as the sum or difference of two functions. answers: 1/2(...

calc - Where do I start to prove this identity: sinx/cosx= 1-cos2x/sin2x please ...

trig - cotx = -2 and 0 less than or equal to x less than or equal to pi Find ...