Posted by **aaa** on Saturday, February 2, 2013 at 4:40am.

kos^2 theta - sin^2 theta = 0.25

- Math(Trigonometry) -
**Reiny**, Saturday, February 2, 2013 at 8:40am
the left side is a well know identity,

cos^2 A - sin^2 A = cos 2A

so we have:

cos 2Ø = 1/4

2Ø = 75.52° or 2Ø = 284.48°

Ø = 37.76° , 142.24°, ...

or

Ø = .659 , 2.4825 ... in radians

general solution in radians:

.659 + kπ/2 , where k is an integer,

2.4825 + kπ/2, where k is an integer.

general solution in degrees:

37.76° + 90k° , 142.24° + 90k°

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