Algebra/ trig help please?

For a particular angle theta, the cosine function has the following values within one

cycle of the function.

Cos 0 =3, cos pi/4=0, cos pi/2 =-3, cos 3pi/4=0, cos pi = 3

What is the rule for the cosine function?

Y = 1/3 cos2 theta

Y= 2cos3 theta

Y= 3cos theta/2

Y= 3cos2 theta

Please explain how you get the answer as well as what the answer is. I’m having a hard time understanding this. Thanks for any help! 🙂

1 Answer

  • at theta =0, cos ntheta = 1

    only answer 3 and 4 agree with this

    at theta = pi/4 (45deg) cos = .707, cos 2theta = 0, cos theta/2 =.924

    only eq 4 agrees with this.

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