So far I have expanded sin(θ−30°)Quote:

The first three terms of an arithmetic series are √3cosθ, sin(θ−30°) and sin θ, where θ is acute. Find the value of θ.

to get;

how do I find theta? Is there a formula?

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- Dec 26th 2009, 07:09 AMTweetytrig arithmetic series..Quote:

The first three terms of an arithmetic series are √3cosθ, sin(θ−30°) and sin θ, where θ is acute. Find the value of θ.

to get;

how do I find theta? Is there a formula? - Dec 26th 2009, 07:23 AMe^(i*pi)
- Dec 26th 2009, 09:23 AMSoroban
HGello, Tweety!

Quote:

The first three terms of an arithmetic sequence are: .

where is acute. . Find the value of

We have: .

Subtract [2] from [1]: .

Subtract [3] from [2]: .

Equate [4] and [5]: . .

Divide by 2: .

Since

. . we have: .

. . . That is: .

Therefore: .