Trig question (1 Viewer)

[JasonNg]

How do i solve this?

sin ( 360 - x ) . tan (90 - x)

 

[jet]

I think you're missing something. There's no "=" sign anywhere, so this isn't an equation.

 

[JasonNg]

the question says to simplify :S

 

[jennduong]

sin(360 - x) = -sin x [because sin is negative in the 4th quadrant]

tan(90 - x) = cos x [positive because tan is positive in the 1st quadrant and cotx = 1/tanx]

Putting it together:

sin(360 - x) * tan(90 - x) = (-sin x) * cot x

= -sinx * (cosx / sinx) [ because cotx = cosx / sinx]

= -cosx

 

[Carrotsticks]

sin(360 - x) = -sin x [because sin is negative in the 4th quadrant]

tan(90 - x) = cos x [positive because tan is positive in the 1st quadrant and cotx = 1/tanx]

Putting it together:

sin(360 - x) * tan(90 - x) = (-sin x) * cot x

= -sinx * (cosx / sinx) [ because cotx = cosx / sinx]

= -cosx

Bit of a typo here.

And nice to see you're back in the game, jetblack2007.