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November 21, 2014

November 21, 2014

Posted by **Joanie** on Monday, March 30, 2009 at 7:08pm.

I have to choose from the following four answers:

hyperbola (angle of rotation 45)

hyperbla (angle of rotation 60)

ellipse (angle of rotation 90)

ellipse (angle of rotation 30)

I used the discriminant (-148) is less than 0--equation on an ellipse and A does not equal C.

I am using the formula tan2theta=B/A-C to find the angle of rotation.

tan2theta = -6(dq.ft.6)/13-7 = -6(sq.rt.6)/6 =-(sq.rt. 6)

tan2theta=-67.79

theta=-33.89 degrees

Where have I gone wrong finding the angle of rotation? I have my calculator set to degrees.

Thanks for helping!

- PreCalculus -
**bobpursley**, Monday, March 30, 2009 at 7:40pmUsing

Theta = 0.5 arccot((a-c)/2/b)

Theta= 1/2 arccot((6/2)/6sqrt6

=1/2 arccot(1/2sqrt6)

I get slightly less than 40 deg

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