## anonymous 4 years ago If cos θ = 4/5, what is cos (- θ)?

1. anonymous

$\cos (- \theta)=\cos(\theta)= 4/5$$\theta$

2. anonymous

yeah i know you switch it, but now do I just plug that in my calculator or leave it?

3. anonymous

just for 4/5

4. anonymous

cosine is even function, f(-x) = f(x)

5. anonymous

ohkay so it would be cos(- θ)= 4/5?

6. anonymous

Try drawing the two triangles on a coordinate grid. |dw:1349313476943:dw|

7. anonymous

ohkay, im not sure how that helps me?

8. anonymous

Do you know what the definition of cosine is?

9. anonymous

no

10. AravindG

cos(-theta)=cos theta

11. anonymous

so then its just 4/5

12. AravindG

yep!!!

13. anonymous

thanks!!