Posted by Abbey on .
Eliminate the parameter and write the corresponding rectangular equation whose graph represents the curve.
x = sec Q
y = cos Q
x^2 + y^2 = 1/cos^2 + sin^2/cos^2 =
x^2(1 +sin^2) = x^2(2cos^2)
x^2(21/x^2) = 2x^2  1
x^2  y^2 = 1
My teacher said to use secant*cosine = 1. Please explain!!

Math 
Reiny,
Isn't sec x = 1/cosx ??
so isn't (secQ)(cosQ)
= (1/cosQ)(cosQ) = 1 ???
so we know
secQ(cosQ) = 1
xy=1
looks like we got our equation!