## marcoduuuh 2 years ago Fill in the blank Cos _____ equals √3/2 A. 75 B. 30 C. 45 D. 60

1. tomo

find inverse cos (sqrt(3)/2)

2. marcoduuuh

How do I do that?

3. tomo

ok, one moment. I'm close.

4. tomo

ok, imagine you have a 30 60 90 triangle |dw:1358813789639:dw| cos(30) = sqrt(3)/2 inverse cos (30) = 1/cos(30) 1/cos(30) = 1/(sqrt(3)/2)) 1/cos(30) = 2/(sqrt(3))

5. marcoduuuh

6. tomo

actually i messed up a bit on the last part

7. RyanL.

$\cos x=\frac{\sqrt{3}}{2}$$x=\cos^{-1}\frac{\sqrt{3}}{2}$

8. RyanL.

plug that into a calculator and see what you get

9. tomo

cos(30) = 2/sqrt(3) inverse cos (30) = 1/cos(30) 1/cos(30) = 1/(2/sqrt(3)) 1/cos(30) = (sqrt(3)/2))

10. tomo

you do not need a calculator to solve this.

11. marcoduuuh

x=60?

12. tomo

actually x= 30. cos(30) = 2/(sqrt(3)) and cos^-1(30) = sqrt(3)/2

13. marcoduuuh

Thank you!

14. tomo

yw

15. tashastevens1

i believe it's 30 ...just plug into calculator. ;D

16. marcoduuuh

Did it, it's 30. Thank you. (:

17. tashastevens1

im sooo un-usefull on here ...-__- i tried haha at least it was the right answer this time ...