Posted by **Sophie** on Tuesday, June 16, 2009 at 5:26pm.

For 4x^2 - 4xy + y^2 = 4 find θ, the angle of rotation about the origin, to the nearest degree?

a) 27°

b) 63°

c) 333°

d) 307°

I got A, is this right?

- Math -
**Reiny**, Tuesday, June 16, 2009 at 6:44pm
I had -26.6 or 333.4 in a positive direction

tan 2θ = B/(A-C)

= -4/(4-1) = -4/3

2θ = -53.13

θ = -26.13

- Math -
**Sophie**, Tuesday, June 16, 2009 at 6:49pm
oh, so it is C?

- Math -
**Reiny**, Tuesday, June 16, 2009 at 6:51pm
has to be

didn't you also get -26.6 degrees?

that is not given.

What angle is coterminal with -26.6 ?

It is 333.4 .

- Math -
**Reiny**, Tuesday, June 16, 2009 at 6:55pm
Here is a webpage that has your type of question

http://education.yahoo.com/homework_help/math_help/problem?id=miniprecalcgt_8_1_1_26_70

press "STEP" to go through the problem.

Notice they leave their angle as a negative.

- Math -
**Sophie**, Wednesday, June 17, 2009 at 3:57pm
oohh yes i did! thanks!!

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