Find in degrees the numeric value of the acute angle of rotation that eliminates the product term from the equation
7
x
2
+
24
x
y
−
34
x
+
24
y
−
185
=
0
If r = x
y
1
1 0 g
and A = 0 1 f
g f c
show that r^T Ar = 0 is the equation of the
circle in R^2 with centre (−g, −f) and radius square root(g^2 + f^2 − c).