Trig equation: Find all soln's of 2cos(theta)+1=0 on the interval [0,2pi)

[clossan88]

Hello all! Can't seem to get a right answer after multiple tries.

Question:

Find all solutions of the equation 2cos(theta)+1=0 on the interval [0,2pi). Theta=? . If you have more than one solution enter your largest solution.
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I got cos(theta)=-1/2, so theta must = 2pi/3 or 4pi/3?

Thank you all for your help!

 

[tkhunny]

Hello all! Can't seem to get a right answer after multiple tries.

This is incorrect. You have the correct answer. I'm guessing you just don't know what the answer software wants.

Question:

Find all solutions of the equation 2cos(theta)+1=0 on the interval [0,2pi). Theta=? . If you have more than one solution enter your largest solution.
_____________________________________________________________________________________________________________________
I got cos(theta)=-1/2, so theta must = 2pi/3 or 4pi/3?

Thank you all for your help!

Which is the greater of the two? How does it want you to enter data. Does it want 240º? Does it want (4/3)pi? Is there an alternate keyboard so you can actually enter \(\displaystyle \pi\)?

 

[clossan88]

This is incorrect. You have the correct answer. I'm guessing you just don't know what the answer software wants.


Which is the greater of the two? How does it want you to enter data. Does it want 240º? Does it want (4/3)pi? Is there an alternate keyboard so you can actually enter \(\displaystyle \pi\)?

Thank you so much tk! You lit the lightbulb in me. It is the software! (well me). It was the "pi" that was not computing because I didn't add the * sign between 4 and pi . I was really starting to feel helpless lol.

I truly appreciate your help!
-Carlos