<PRE><B>Question 860522</B>
find the acute angle of rotation x that eliminates the xy term of 
2x^2 + sqrt3*xy + y^2 - 8 = 0
A = 2 ; B = sqrt(3) ; C = 1
-----
cot(2t) = (A-C)/B = (2-1)/sqrt(3) = 1/sqrt(3)
tan(2t) = sqrt(3)
2t = 60 degrees
t = 30 degrees
-------------------------
Answer: b
Cheers,
Stan H.
======================
a-28.1 degrees
b-30
c-45
d-60
</PRE>