- #1
popsquare
- 8
- 0
I am looking for the angle needed to rotate the conic to eliminate the xy-term
but the angle I find is negative and I need the counter-clockwise angle of rotation to satisfy 0 < theta < 90 degrees. Where am I going wrong? Or what else do I need to know? Thank you for your help.
I have this equation of a conic and I am supposed to find only the angle of rotation with this formula:
cot 2(theta) = A - C / B
The equation I am using is this:
I then solve for theta plugging these A = 153 , B = -192 , C = 97 into
cot 2(theta) = A - C / B
I get this equation: cot 2(theta) = -56/192
Let theta = 2*theta
Then :
cot theta = -56/192
I take the inverse tangent to find 2*theta and then solve for theta like this:
arctan ( 192/-56) = -73.7398 degrees
Remember I let theta = 2*theta
-73.7398 = 2*theta
theta = -37 degrees.
Is there a way for -37 degrees to satisfy the original question?
but the angle I find is negative and I need the counter-clockwise angle of rotation to satisfy 0 < theta < 90 degrees. Where am I going wrong? Or what else do I need to know? Thank you for your help.
I have this equation of a conic and I am supposed to find only the angle of rotation with this formula:
cot 2(theta) = A - C / B
The equation I am using is this:
153x^2 - 192 xy + 97y^2 - 30x -40y - 200 = 0
I then solve for theta plugging these A = 153 , B = -192 , C = 97 into
cot 2(theta) = A - C / B
I get this equation: cot 2(theta) = -56/192
Let theta = 2*theta
Then :
cot theta = -56/192
I take the inverse tangent to find 2*theta and then solve for theta like this:
arctan ( 192/-56) = -73.7398 degrees
Remember I let theta = 2*theta
-73.7398 = 2*theta
theta = -37 degrees.
Is there a way for -37 degrees to satisfy the original question?
Last edited: