Friday

November 21, 2014

November 21, 2014

Posted by **Pre Calculus** on Sunday, November 15, 2009 at 10:07pm.

why is sin(-20)/cos 380

equal to tan (-200)

- Pre Calculus -
**bobpursley**, Sunday, November 15, 2009 at 10:12pmI covered this previously.

Sin(theta)=sin(theta+360) in degrees

Sin(-theta)=sin(Theta) in degrees

sin(-20)=-sin(20) =-sin(20+360)=-sin(380)

then...

Tan(-theta)=-tan(theta).

Your refusal to post some sort of a meaningful name in the name box is not helping you get meaningful assistance.

**Answer this Question**

**Related Questions**

PreCalculus - why is -sin(380)/cos (380) equal to -tan(200) I don't see how it's...

Pre Calculus - ok I appologize for my stupidity... I'll answer your question... ...

Pre-Calculus - I don't understand,please be clear! Prove that each equation is ...

Pre-Calculus - Prove that each equation is an identity. I tried to do the ...

Pre Calculus - Verify the identity: cos x + sin x tan x = sec x.

Pre Calculus - Use one of the identities cos(t + 2šk) = cos t or sin(t + 2šk) = ...

Pre Calculus - Use one of the identities cos(t + 2šk) = cos t or sin(t + 2šk) = ...

pre-calculus - cosx= -8/17, 180<x<270 find; sin(x/2) cos(x/2) tan(x/2)

Trig - Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 < v < ...

Pre calculus - How do you work this problem? Find the exact value of sin 2u, cos...