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January 26, 2015

January 26, 2015

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).

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